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RO-DRIP® User Manual - TRICKL-EEZ

1. Figure 4 21 Steps for Connecting a Lateral to a Transfer Tube Without Fittings Use the procedure shown in figure 4 22 to connect a transfer tube to a lateral using a wire tie Figure 4 22 Steps for Connecting a Lateral to a Transfer Tube Using a Wire Tie Use the procedure shown in figure 4 23 to connect a transfer tube to a lateral using a lock sleeve fitting Figure 4 23 Steps for Connecting a Lateral to a Transfer Tube with a Fitting RO DRIP USERS GUIDE RD4 5 The Roberts Difference The unique polyethylene material blend used to make RO DRIP provides strength as well as flexibility and memory The result is reliable leak free connec tions to transfer tubes and fittings 4 9 4 10 INSTALLATION AND STARTUP SPLICING LATERALS Drip tape laterals can be spliced using tubing 510 x 610 OD and wire ties fig 4 24 or by using a locking sleeve fitting fig 4 25 Figure 4 24 Splicing a Lateral Using Poly Hose Figure 4 25 Splicing a lateral Using a Locking Sleeve Fitting and Wire Ties Figure 4 26 Closing a Lateral Using a Closing Band TERMINATING LATERALS Drip tape laterals can be terminated using a closing band fig 4 26 or a lock sleeve end cap fitting fig 4 27 Figure 4 27 Closing a Lateral Using an End Cap RO DRIP USERS GUIDE INSTALLATION AND STARTUP STARTUP PROCEDURE Before you begin irrigating it
2. fungicides Water Source cee eee ee eee well Fertigation yes Ground cover ee none Line flushing monthly Crops rotated with none Filter back flushing automatic Time to maturity 20 60 days Average yield depends on market Duration of tape installation 3 6 months Drip Tape RO DRIP 8 8 40 8 mil 8 in spacing 40 GPH per 100 ft 5 8 in diameter 200 mm 20 cm spacing 497 LPH per 100 m 16 mm diameter RO DRIP USERS GUIDE B 13 B 14 CROP PRODUCTION Peppers Peppers are a warm season crop Pepper plants can be injured or killed by frost and grow best in soil temperatures above 65 F 17 C and in air temperatures of 70 to 80 F 20 to 25 C Transplanted peppers root only to a depth of about 2 ft 60 cm but use soil moisture efficiently Young pepper plants are relatively resistant to water stress but may show slower development and reduced yields Peppers are usually transplanted in single rows on 36 in 91 cm beds with 12 in 130 cm in row spacing or on 72 in 183 cm beds with double rows spaced 12 to 18 in 30 to 46 cm apart and staggered on either side of the drip lateral with 12 to 18 in 30 to 46 cm in row spacing Plastic mulch in combination with drip irrigation can be used to increase yields EXAMPLE Peppers Pennsylvania USA Operation Auxiliary Equipment Crop
3. Y Y a 3m 09m 2 1m Operation Auxiliary Equipment Copes ets CES ec sugarcane Primary filtration sand media Location e Venezuela Secondary filtration Field size 10 400 acres 4 200 ha screen amp sand separator Plants per acre 27 000 67 000 per ha SUDMAING ie ae CARA ee de A PVC SEASON es ateus a iii a year round Mulch u e ue none Soil type LL eL Lu LL rE sandy loam f Maximum ET 0 28 in 7 mm per day Management 0peration Water Source deep well Irrigation frequency 3 4 days Groundcover none rrigation duration 24 hours Crops rotated with none Chemigation yes Time to maturity 30days Fertigation yes Average yield 46 tons acre 103 tons ha Line flushing weekly Duration of tape installation 8 years Filter back flushing weekly Drip Tape RO DRIP 13 12 24 13 mil 12 in spacing 24 GPH per 100 ft 5 8 in diameter 330 mm 30 cm spacing 298 LPH per 100 m 16 mm diameter RO DRIP USERS GUIDE B 7 CROP PRODUCTION Potted Plants Potted flowers and other plants can be irrigated with drip tape either directly or with the use of a capillary mat For direct irrigation lay he
4. Ideally each zone should be sized to fully utilize your water supply although this is not always practical In some cases it is desirable to irrigate more than one zone at a time but it is never possible to simultaneously irrigate more acres hectares than the number given above FILTRATION Filtration Requirements for Drip Irrigation The main purpose of filtration is to keep your emitters clean and working properly Maintaining clean emitters is as important to your drip system as water is to your crops Two common sources of emitter clogs in line particulate suspended soil algae etc and chemical precipitates can and should be prevented by proper filtration and water treatment NOTE Filtration equipment is a crucial component of your drip system Resist the temptation to save money on unreliable or inappropriate filtration equipment it is the heart of your system and should be the right equipment for your farm water source In addition to filtration chemical water treatment may be necessary to control pH or to remove algae bacterial slime and mineral participates that can clog emitters See MANAGE MENT Water Treatment for more on water treatments Filter Types and Filter Selection There are several types of filter systems available Your choice among them should be based on careful consideration of the following factors e A thorough analysis of your water supply including particle size and concentration Filtration re
5. e Run length Placement of laterals depth spacing position and run length Emitter spacing Flow rate Drip tape wall thickness Drip tape diameter Table 3 1 summarizes these parameters and their effect on performance Each is discussed in greater detail in the remainder of this section Lateral Run Length and its Effect on Uniformity Length of run has a direct effect on the uniformity DU of each drip lateral If laterals are too long pressure losses cause a higher application rate at the beginning of the run than at the end In general longer run lengths with good uniformity are possible with low flow rate and or large diameter drip tapes although all drip tapes have their limits The DU of a single lateral is determined by its length slope operating pressure flow rate x and Cv Performance Charts published by most drip tape manufacturers summarize all of these effects and tell you how long your drip tape runs can be for a given set of conditions Consult the Roberts Irrigation performance charts for all RO DRIP products Example You plan to use a 13 mil RO DRIP product with a performance chart in appendix D to irrigate cotton There is a 0 5 downhill slope and the distance from the supply manifold to the end of the field is 1000 ft 305 m You require a DU of 85 for each lateral and the average pressure of the supply manifold is 8 PSI 55 bar Solution Pressure 8 PSI 55 bar Target EU 85 Run L
6. 3 5 days Water Source deep well Chemigation yes Groundcover NONE Tertigation yes Crops rotated with broccoli cauliflower Tine flushing at startup Time to maturity 180 days Filter back flushing automatic Average yield 60 tons acre 134 tons ha Duration of tape installation 6 months Drip Tape RO DRIP 8 12 24 8 mil 12 in spacing 24 GPH per 100 ft 5 8 in diameter 200 mm 30 cm spacing 298 LPH per 100 m 16 mm diameter RO DRIP USERS GUIDE CROP PRODUCTION Strawberries Strawberry plants are extremely salt sensitive Strawberry production with relatively salty water is a remarkable success story that illustrates the ability of drip irrigation to manage salinity and meet the needs of row crops under adverse conditions Transplants are usually planted in the early fall three or four rows per bed Beds are spaced 60 to 64 in 147 to 163 cm between centers with two drip laterals per bed placed between rows In row spacing of 9 to 10 in 23 to 25 cm is frequently used Polyethylene mulch is typically used to increase bed temperature and maintain winter growth Strawberry plants must be protected from frost Excessive salinity decreases root development water uptake growth rate and fruit yield Where salts are a problem it is important to leach with solid set sprinklers before be
7. Moisture level does not return to field Too little water applied Increase duration capacity after each irrigation MONITORING To achieve the high yields and water savings possible with drip irrigation it is necessary to monitor your system and make adjustments to fine tune the amount of water and nutrients applied In addition careful system monitoring gives advance warnings of potential problems Monitoring Performance Monitor the performance of your system by taking readings from all of the flow meters and pressure gauges at regular intervals Flow meters There should be at least one flow meter installed on the mainline to indicate the total amount of water being applied to the field Once your irrigation schedule has been determined read the flow meter to confirm that the system is applying the amount of water it was designed to apply Because of the large number of variables at play in an irrigation system the measured appli cation rate cannot be expected to be exactly the same as the predicted rate However a large difference indicates either a problem in your calculations or a physical system problem such as a broken or clogged line If the results are not what you expect identify and fix the problem Flow meter readings can also indicate problems that can occur mid season To make use of this valuable information to measure and record flow meter readings for the new system and on a regular basis thereafter Table 5 5 shows som
8. Operation Auxiliary Equipment COP aeieea e a celery Primary filtration sand separator Location Baja California Mexico Secondary filtration none Field size 100 acres 40 ha SUDMAING in deci 6760393538768744 layflat Plants per acre 120 000 296 500 per ha Muley a 27 sau kayana Se eee oe none Season Mar Apr Sep Oct I Planting method direct seeded Management Operation Soil type aa sandy loam hrigation frequency 1 3 days Maximum ET 0 35 in 9 mm per day Irrigation duration 6 12 hours Water Source deep well Chemigation yes Ground cover sees NONE Rertigati n l aa a n yes Crops rotated with ne R E ante creer Line flushing at startup Time to maturity 90 60 days Filter back flushing automatic Average yield 500 boxes acre 1235 per ha Duration of tape installation 60 days Drip Tape RO DRIP 5 8 40 5 mil 8 in spacing 40 GPH per 100 ft 5 8 in diameter 127 mm 20 cm spacing 497 LPH per 100 m 16 mm diameter RO DRIP USERS GUIDE CROP PRODUCTION Sugar Cane Sugar cane is a 2 year crop in some parts of the world and a 1 year crop in others It is typically grown from a mechanically planted stalk every 48 in 122 cm in the row Rows are spaced in pairs 36 in 91 cm apar
9. ROBERTS IRRIGATION PRODUCTS INC RO DRIP User Manual INTRODUCTION WHAT IS DRIP IRRIGATION Drip irrigation is about delivering water nutrients and chemicals where you want them when you want them Using a network of pipes and drip laterals a drip system releases water and nutrients uniformly through precision manufactured emitters directly into the root zone Near optimum soil moisture levels are maintained and rapid response can be made to a variety of crop needs The precise delivery of water and nutrients made possible by drip irrigation gives you a level of control over the soil environment that is not possible with traditional sprinkler or furrow irrigation This means better control of crop health water and fertilizer usage harvest time and your bottom line Following are some of the many benefits reported by growers who have converted from sprinkler and furrow irrigation to drip irrigation Improved crop yield quality and uniformity Better control over harvest time and market timing Reduced water consumption Reduced energy consumption Reduced cost of chemicals and fertilizer Reduced field labor cost Reduced disease Better weed control Better utilization of uneven terrain More land can be utilized if water is a limiting factor Reduced environmental impact from runoff and percolation of chemicals fertilizers and salts This is a remarkable set of benefits for any single technology to
10. Record readings from all pressure gauges and flow meters UJI MN W onou 1 o RO DRIP USERS GUIDE 4 11 MANAGEMENT The three critical components of a drip system management program are scheduling monitoring and maintenance Each has requirements that differ from traditional furrow and sprinkler irrigation Scheduling must be carefully planned to keep the soil in the root zone near field capacity providing ideal conditions for plant growth Monitoring of pressures flow rates and soil moisture is neces sary to continually fine tune your irrigation schedule Finally a regular maintenance program is required to keep the drip emitters clean and free of clogs that can reduce efficiency and damage your system This section tells you how to schedule monitor and maintain your drip irrigation system for years of successful operation Emphasis is placed on diligent planning and adjustment of your program to maximize crop performance and avoid potentially costly problems The section finishes with management and maintenance issues associated with chemical fertilizer injection and salinity management KEN CIONS e Take the time to learn train and implement some new ways of irrigation management The three components of a successful drip irrigation management program are scheduling monitoring and maintenance The goal of drip irrigation scheduling is to replace soil moisture as it is lost to evapotranspiration Small
11. ee eee eee eee eee ee pot mix Irrigation frequency every 3 days Water Source municipal Irrigation duration 15 30 min Ground cover none Chemigation yes Crops rotated with NONE Tertigation yes Time to maturity ima manao k gin 60days ine flushing every crop Average yield 35 000 acre 86 000 ha Filter back flushing monthly Duration of tape installation 2 years Drip Tape RO DRIP 8 12 24 8 mil 12 in spacing 24 GPH per 100 ft 5 8 in diameter 200 mm 30 cm spacing 298 LPH per 100 m 16 mm diameter B 8 RO DRIP USERS GUIDE CROP PRODUCTION Tomatoes Tomato transplants are typically planted on single row beds spaced 60 to 72 in 152 to 183 cm center to center with 18 to 20 in 46 to 51 cm in row spacing Stakes are placed between every three or four plants Twine is tied to the stakes and around the tomato plants to support their heavy fruit crop Tomatoes can be grown on almost any moderately well drained soil from deep sand to clay loam The highest production is usually achieved from well drained loamy soil types You can also use plastic mulch to achieve better control of soil conditions and produce higher yields In the following example the grower uses plastic mulch and RO DRIP drip tape to success fully grow fresh market tomatoes EXA
12. AR 046 inches per hour 1 17 mm per hour 6 feet x 62 6 x 62 or 1 1 in per day The required flow rate will be lateral spacing in meters x water supply capacity LPM 1 67 x tape flow rate LPH 100 m N acres From the above the system is capable of delivering more than three times the application rate required during peak ET but it requires a higher flow rate than your water supply can pro vide A possible solution to this problem is to divide the field into three equally sized zones and irrigate one zone at a time Doing this the maximum application rate to the field will be 1 1 3 37 in per day 94 mm per day and 1097 GPM 4512 LPM will be required of your water sup ply See Dividing Your Field Into Independent Zones in this section RO DRIP USERS GUIDE 3 11 RD3 12 Ea The Roberts Difference RO DRIP XL is a premium quality 7 8 in diameter drip tape product designed for long lateral runs It is available in several emitter spacings and flow rates and has been successfully used for lateral runs over 1 4 mile 0 4 km long 3 12 DESIGN Table 3 6 Guidelines for Selecting Wall Thickness for Drip Tape THICKNESS APPLICATION AND FEATURES 5 mil 0 127 mm olun number rocks me pews applications where installation cost is very important efirst time drip tape users who desire a thin walled drip tape si 0 152 mm i ip tape u whe i in w rip tap s experienced drip ta
13. Procedure later in this section Drip tape laterals can connect to rigid PVC layflat or polyethylene hose submains with a few basic fitting types See the Roberts Irrigation Product Catalog for a complete list of Roberts fittings and tubing Connecting to PVC submains Drip laterals can be connected to PVC sub mains either directly with fittings or through transfer tubing fig 4 10 Both glued fittings and gasketed fittings can be used In either case fittings are available that directly con nect PVC submains to the following Drip tape using a lock sleeve fitting Transfer tubing using an external compression fitting Transfer tubing using an internal barb See Connecting a Transfer Tube to a Lateral below for instructions on connecting a Figure 4 9 Field Nursery Installation transfer tube to a drip tape lateral once it has been connected to the submain Figure 4 10 Common Fittings for PVC Submains RO DRIP USERS GUIDE 4 5 4 6 INSTALLATION AND STARTUP For either fitting type an appropriately sized hole must be drilled that is free of gaps cracks or splits fig 4 11 Only clean holes will allow a proper connection Use the procedure shown in figure 4 12 to connect a fitting or 4 13 to directly connect a trans fer tube to a PVC submain Figure 4 11 Creating a Hole in a PVC Submain Figure 4 12a b Connecting a Gasketed Fitting to a PVC Submain Figure 4 1
14. Tons metric 0 907 Metric Tons Pounds 2205 Tons short Tons long 0 893 Metric Tons Tons Long 0 984 Tons short Kilograms 907 2 Metric Tons Tons Short 1 1 Tons short Pounds 2000 Tons long Metric Tons 1 02 Tons long Tons short 1 12 Tons long Pounds 2240 APPENDIX F ENGINEERING CONVERSION FACTORS YIELD To Convert Multiply by To Convert To Multiply by Metric Tons per Hectare US Tons per Acre US Tons per Acre Metric Tons per Hectare Kilograms per Hectare Pounds per Acre Pounds per Acre Kilograms per Hectare Cubic Meters per Hecare Bushels per Acre Bushels per Acre Cubic Meters per Hectare APPENDIX F ENGINEERING CONVERSION FACTORS FLOW Multiply Multiply Acre Inches per 24 Hours Gallons per Minute Cubic Meters per Hour Liters per Second 0 278 Cubic Feet per Second Gallons per Minute Cubic Meters per Second Cubic Feet per Second 35 31 Cubic Feet per Second Acre in per Hour approx Cubic Meters per Second Gallons per Minute 15850 Cubic Feet per Second Acre Ft per Day approx Liters per Minute Cubic Feet per Second 5 89x10 4 Cubic Feet per Second Liters per Second 28 32 Liters per Minute Cubic Gallons per Second 4 40x103 Cubic Feet per Second Liters per Minute 1699 Liters per Minute British Gallons per Minute 13 2 Cubic Feet per Second Cubic Meters per Second 0 0283 Liters per Second Cubic Meters per Hour 3 6 Gallons per Minute Cubic Meters per
15. because of its simple and functional design Simple injectors such as the Tube Type Shank are easy to build although extreme care must be taken to eliminate all sharp surfaces More advanced injectors which allow high speed installation of thin walled tapes can be pur Pay attention to the following important factors when you design or purchase an injection shank The installation tube should have a flared opening and should be free of burrs nicks sharp edges weld lines or seams that can cause damage to the drip tape The diameter of the installation tube should be as small as possible 1 in Schedule 40 steel for standard 5 8 in drip tape or 1 25 in for 7 8 in drip tape The bottom of the installation tube should be at the same depth as the bottom of the shanking tool e The drip tape spool should be positioned close to the injection tube directly above it if possible e The drip tape spool should be mounted on a shaft that can spin freely stationary shafts will be damaged by the spool hubs or can damage spool hubs The shaft should have a braking system that can provide drag to prevent overspinning of the spool when the tractor stops e Wood or metal disks should be used to support the cardboard drip tape spools The injection shank can be mounted on a toolbar with other equipment to perform several Figure 4 4 Tube type injection shank Courtesy of Andros Engineering Figure 4 5 Combination Bed Shaper Plasti
16. been used Requires careful design and maintenance The system should be designed for easy flushing of laterals Operation of system during light rain may be required to prevent salt from leaching into the root zone DESIGN Selection of Emitter Spacing Common drip tape emitter spacings are 4 8 12 16 and 24 inches 10 20 30 40 and 60 cm Narrowly spaced emitters are useful in sandy soil or where high flow rates are desired Wider spacings provide lower flow rates that make longer lateral runs possible See table 3 3 for guidelines on selecting emitter spacing These are general descriptions only Table 3 3 Guidelines for Emitter Spacing EMITTER SPACING APPLICATIONS AND FEATURES CROPS greenhouse and field flower applications Flowers ach short lateral runs Potted plants results in good wetting patterns in sandy soils every high flow rate results in good wetting patterns in sandy soils Flowers I aids in germination of seeds Potted plants 8 inch provides a relatively high flow rate Strawberries Most vegetables ecrops in most soils Potted plants lower flow rate than 8 in 20 cm spacing Strawberries j longer runs are possible due to lower flow rates Most vegetables Ae nch Sugar cane Potatoes Melons lower flow rate for improved infiltration of heavy soils Melons longer runs possible than with 8 or 12in 20 or 30 cm Corn 16 inch spacing Cotton may not effectively ge
17. for growing that crop with drip irrigation The description includes a specific example of how one experienced grower in one geographic region has grown that crop Due to differences in climate and soil type the best practice for your field may be different but the examples can give you an idea of what is required It always helps to learn from the experience of others The crops described in this appendix are OOS u aasan iss haqa dh cee Alcea a dl Sed d A Aru Erra 4 Sab D2 SI AWIOCNICS ses ene AMES A TA ea ente dte ais pesat ia D3 MODS edi tal lesa ea GES RES at uquy ypas D4 LEMU S ss ia so ee me one t i Lee met cec DAAR AE AA AUDA R E D5 CEE rnap teca ae rtamamipaiees ions ere Q paqu hucha aaa pes D6 Sugar CAE 5 2020 us reia Ir PES UGT O ES PRO RI ee GE O a Ga Ees D7 POC PIA Sat supay masia miu tuni win Made aa a thems mews ee D8 TOMO CS r esa a ES A0 S ADA E MSA mish E A A easton etnies ound D9 POUGUOES aya State tacs ame kp saus Sona ions Ei t nbd one a D10 CORON nenret 24 baba eee A4 be boa Cuida aa oA Gaba Geel D11 COMM yayan saa um apa Led paita halia un o pusa p EC Ec D12 FICURIOWGIS 2 442 444 reenen hea eaa eaae eenei D13 Pepper resa sem a E aoaea papua sia ask habasta D14 All of the crops that are irrigated vvith drip tape could not possibly be included in this appendix If you do not find your crop listed above contact Roberts Irrigation we may have it on file B 2 CROP PRODUCTION Onions Onions a
18. perform retrieval in the morning before the sun heats up the drip tape Figure 6 3 End of Row Retrieval TIP If the spool is spinning faster than the tape appears to be coming off of the ground the tape is stretching Another way to check for stretching is to stop the retrieval head and unlock the spool If it backspins the tape is stretching Over the row extraction Over the row extraction is not as common as end of row extraction but it is sometimes the best choice when laterals are buried In over the row extraction one or more retrieval heads are mounted to a tractor tool bar fig 6 4 A system of guides brings the tape to the spool as it is pulled off the surface Over the row extraction is less prone to damaging the drip tape by stretching or scraping but it can be more costly and time consuming than end of row extraction If the drip tape is buried less than 3 in deep and is a suitably heavy gauge it can usually be pulled through the soil In some cases it helps to soften the soil around the laterals by irrigating for a period of time before removal RO DRIP USERS GUIDE RETRI EVAL AN K Ll N d c RO RES L mn j NA Nan se saa Bars x lt CCC CO nta Figure 6 4 Over the Row Retrieval Subsurface Drip Systems Deep subsurface drip laterals can be removed over the row by using an appropriate tool to open the bed above the tape Use a furrower or a disc type opene
19. using a direct transfer tube or using a fitting Figure 4 18 shows some common fittings for connecting a layflat hose submain to a transfer tube or lateral Figure 4 18 Common Fittings for Layflat Submains RO DRIP USERS GUIDE 4 7 RD4 4 The Roberts Difference Roberts Irrigation Products manufactures a premium quality line of polyethylene hose products which are available in all of the sizes commonly used for drip irrigation transfer tubes 4 8 INSTALLATION AND STARTUP Use the procedure shown in figure 4 19 to connect a fitting to a layflat submain or figure 4 20 to directly connect a transfer tube See Connecting a Transfer Tube to a Lateral below for instruc tions on connecting the transfer tube to a drip tape lateral once it has been connected to the submain Figure 4 19 Connecting a Fitting to a Layflat Submain Figure 4 20 Directly Connecting a Transfer Tube Layflat Submain CONNECTING A TRANSFER TUBE TO A LATERAL Transfer tubes connect submains to laterals Smaller transfer tubes 1 8 to 3 8 tubing can be directly connected to laterals Larger tubes 0 510 x0 610 for standard 5 8 in drip tape are connected using wire ties Finally a lateral can be connected to a transfer tube with a barbed lock sleeve fitting RO DRIP USERS GUIDE INSTALLATION AND STARTUP Use the procedure shown in figure 4 21 to directly connect a small diameter transfer tube to a lateral
20. Calibration required High cost Calibration required Must be installed in field for each reading Radioactive requires licensing RO DRIP USERS GUIDE Currently the most common method Accurate in the moisture range of interest to irrigation Can use electronic vacuum transduc er for remote reading Provides a qualita tive reading of wet or dry eLimited effective ness for drip irri gation since soil is kept near field capacity Cost is becoming lower Cost is becoming lower Generally too expensive and complex for practical farm use 5 9 RD5 3 The Roberts Difference RO DRIP employs the largest emitter cross sec tion available on the mar ket to deliver unmatched resistance to plugging While this does not elimi nate the need for mainte nance it can mean the difference between success and expensive failure in applications where water quality is a problem 5 10 MANAGEMENT are operational it is critical that you maintain them properly This includes a regular program of backflushing and or cleaning filters to keep contaminants out of your drip laterals Regular monitoring of pressure differentials across filters is important to indicate whether your back flushing program is adequate In addition sand media should be replaced periodically as it becomes worn Check the owners manual of your specific filter Water treatment Algae bacteria and m
21. Feet of Water Inches of Water 600 F Pounds per Square Inch 0 4335 0 0295 0 0736 Atmosphere at Sea Level Inches of Mercury Inches of Water 600 F Pounds per Square Inch 0 0361 N a S io lt Pounds per Square Inch 0 491 Inches of Mercury 0 883 RO DRIP USERS GUIDE F 5 ENGINEERING CONVERSION FACTORS APPENDIX F ENGINEERING CONVERSION FACTORS WORK AND POWER F 6 Horsepower Foot Pounds per Second Multiply Multiply 0 55 Calories per Second Horsepower 0 0056 Horsepower Watts 745 7 Calories per Second Kilowatts 0 00419 Horsepower Kilowatts 0 7457 Watts Kilowatts 0 001 Horsepower Calories per Second 178 1 Watts Horsepower 0 00134 Foot Pounds per Second Kilowatts 0 000738 Kilowatts Watts 1000 Foot Pounds per Second Horsepower 0 00182 ilowatts Foot Pounds per Second 1356 Foot Pounds Calories 0 3239 ilowatts Calories per Second 238 9 Foot Pounds BTUs 0 00129 ilowatts Horsepower 1 341 Foot Pounds Kilowatt Hours 3 77 10 7 Calories Foot Pounds 3 09 BTU Foot P ounds 718 ilowatt Hours Calories 8 60x102 BTU Calories 252 ilowatt Hours BTUs 3413 BTU Kilowatt Hours 0 00029 ilowatt Hours Horsepower Hours 1 341 Horsepower Hour Kilowatt Hours ENGINEERING CONVERSION FACTORS 0 7457 ilowatt Hours APPENDIX F Foo
22. Sabin Figure 3 1 shows the major components of a typical field layout Design of Submains Figure 3 5 Typical Field Layout The function of a submain or supply man ifold is to distribute water uniformly to a number of laterals For surface or shallow subsurface systems submains are commonly made of polyethylene hose or reinforced flexible PVC layflat on the surface or buried PVC The submains for a deep subsurface system should be PVC When PVC is installed on the surface use a light cover of soil to protect it from UV degradation and algae growth within the pipe that can result from exposure to sunlight Table 3 8 summarizes the features of each type of submain Each submain in your system should supply consistent pressures to all of the laterals attached to it Consult a qualified irrigation designer to specify submain diameters that can meet this requirement as cost effectively as possible Design for Flushing If your system is used for multiple seasons or water quality is poor it may be necessary to periodically flush the laterals by opening the ends to remove sediment with the resulting water flow If flushing is infrequent this may not require any special consideration in the design stage although removable end caps can make the procedure easier In large systems that require frequent flushing flushing manifolds as shown in figure 3 6 can save time and labor Several laterals terminate to a single flushing manifold and
23. Second Feet per Second 3 281 Feet per Minute Miles per Minute 0 000189 Centimeters per Second Miles per Hour 0 0224 Feet per Second Meters per Second 0 305 Centimeters per Second Miles per Minute 0 000373 Feet per Second Miles per Hour 0 68 Feet per Second Kilometers per Hour 1 10 Feet per Second Miles per Minute 0 0114 APPENDIX F ENGINEERING CONVERSION FACTORS PRESSURE AND HEAD g CY 2 D D r Pounds per Square Kg per Square Meter 703 1 Atmospheres Pounds per Square Inch n Pounds per Square In n Pounds per Square Pounds per Square To Multiply To Convert Multipl r u by Bar 0 0689 Atmospheres Inches of Mercury f Atmosphere 0 068 Atmospheres Feet of Water 33 9 ar n Pounds per Square In n Pounds per Square ch ch ch ch ch ch ch Pounds per Square In Pounds per Square Foot Feet of Water 2 31 Bar Pounds per Square Inch 14 5 Inches of Mercury 2 036 Bar Atmosphere at Sea Level 1 013 Pounds per Square Foot Inches of Mercury Pounds per Square Inch 0 00694 Kg per Square Meter Pounds per Square Foot 0 2048 Kg per Square Meter 4 88 Kg per Square Meter Pounds per Square Inch Inches of Mercury Inches of Mercury 0 00142 Atmosphere at Sea Level 0 0334 Kg per Square Meter 345 3 Feet of Water 1 13 Inches of Mercury Inches of Mercury Inches of Water 600 F 13 60 Feet of Water Feet of Water
24. a system that makes maximum use of your existing infrastructure to reduce both capital and labor costs Mei CONG TS e Your drip system design should reflect a careful consideration of soil type water quality evapotranspiration topography crop choice and indigenous pests Collect all of the necessary information before starting Know the look feel and soil moisture content that corresponds to field capacity Your drip irrigation system should be designed to keep the soil moisture close to this value e Obtain a chemical and physical analysis of your irrigation water from an independent laboratory This information will be critical in determining filtration water treatment and fertigation requirements Have a soil sample tested to determine the nutrient content of your soil This will be the first step in developing your fertigation program Make use of your existing infrastructure whenever possible 2 1 The Roberts Difference The broad RO DRIP product line has been successfully used with a diverse variety of crops and field conditions 2 2 PLANNING SOIL TYPE Soil type both texture and structure influences your system design by determining field water requirements and in some cases by limiting your choice of crops Soil type has a great effect on water movement and therefore on root development plant growth and ultimately crop yield and profits Because of its effect on water movement so
25. all installation equipment is free of burrs and other sharp edges e When using clear plastic over drip tape always bury the tape e Operate all systems before any planting begins Chemicals used in irrigation fertigation and water treatment can be extremely hazardous Use extreme caution when mixing handling and injecting any chemicals RO DRIP USERS GUIDE 1 3 The Roberts Difference Roberts Irrigation has set up a special system of support after sale to help you use and maintain your drip irrigation system Our in house technical staff our network of competent dealers and our library of drip irrigation publications and referrals are all at your disposal to help you get the job done PLANNING Before you begin a design you need to identify clear and specific goals based on the answers to questions such as What crops will you grow How often will you rotate Will the system deliver fertilizer and chemicals or only water Will you use plastic mulch These are the starting points for gathering the information you will need to properly plan your system It is also important to know what you have to work with and what other factors will affect the design Soil type climate water quality and availability field topology crop water requirements and indigenous pests can all influence system design as can legal concerns such as environmental and land use regulations Finally proper planning will help you design
26. are seeded on 34 to 40 in 86 to 102 cm single row beds In row plant spacing is regulated by the placement of the individual seed pieces Seed piece spacing ranges from 6 to 7 in 15 to 18 cm for the red varieties and 8 to 12 in 20 to 30 cm for the White Rose and Russet varieties Proper irrigation scheduling is critical to maintain the root zone at the proper moisture level When stressed for water between cycles potatoes tend to develop cracks and become knobby and rough When red varieties are water stressed they tend to develop poor color When exposed to soil moisture levels above field capacity for extended periods of time potatoes frequently develop enlarged lenticels and root or tuber diseases Proper soil moisture during tuber development reduces the severity of scab and is usually adequate to control disease During tuber initiation and early tuber growth until tubers are golf ball sized maintain available soil moisture between field capacity and 20 depletion Avoid planting potatoes in fields with severe scab problems EXAMPLE Sweet Potatoes Central Valley California USA 80 Operation Auxiliary Equipment Crop sisas amuse diuturna i sweet potatoes Primary filtration sand media Location Central Valley California USA Secondary filtration none Field size 50 acres 20 ha SUDANS uy r PE eats eeu layflat Plants per acre 13 000 32 000 per ha Mulchecii
27. can be removed and the tensile strength which are drip tape can be stored on the PVC core The RO DRIP product line gauge products with hig well suited for retrieval and Splices re use These include prod When in field splices are made either for repairing damaged laterals or splicing rolls together special consideration should be taken if the laterals will later be retrieved for re use Twist lock couplings are convenient for making splices but will not easily go through retrieval equipment of 10 13 and 15 mil and will not roll smoothly on a retrieval spool ucts with wall thicknesses When making an in field splice use a Le ase a RI piece of 0 510 x0 610 polyethylene hose and two wire ties as described in INSTALLATION AND STARTUP Splicing Laterals Be sure to tightly wrap the wire ties around the spliced lateral and remove all sharp points so they will not hang up on installation equipment or damage the drip tape Wrap the splice with black electrical tape for further protection Alternatively several heat seal splicers are available now for drip tape Figure 6 1 Manual Retrieval of Drip Tape MANUAL RETRIEVAL Surface and shallow buried 0 3 in drip tape is easily retrieved for disposal without the use of mechanical equipment fig 6 1 If the drip tape is to be re used it can be economically retrieved using an end of row operation as described below in Mechanized Retrieval To manually retrieve drip tape
28. deliver However it is only with careful attention and commitment to the unique requirements of your drip irrigation system that you can enjoy its many potential benefits The Roberts Difference Roberts Irrigation Products Inc has been bringing the benefits of efficient irrigation to growers for over thirty years 11 1 2 INTRODUCTION THE ROBERTS DIFFERENCE An ongoing commitment to tradition integrity and innovation have made Roberts Irrigation Products one of the world s leading producers of micro and drip irrigation products including RO DRIP and RO DRIP XL drip irrigation tapes We have spent enough time in the field to recognize the practical needs of row crop growers like you and have applied the latest precision manufacturing methods to produce a drip tape system that meets these needs Our RO DRIP and RO DRIP XL drip tapes represent the practical application of today s latest technologies to the long felt needs of growers Throughout this manual you will find short captions titled The Roberts Difference located in the margins of each section These captions describe some of the unique benefits of RO DRIP products for drip irrigation users IS DRIP IRRIGATION FOR YOU Each year large numbers of growers around the world convert from traditional irrigation methods to drip irrigation Some are attracted by the promise of higher yields some by the promise of higher profits and some by the simpl
29. drop across filters Pump wear r l pressur r t filter input Graquel pressure LL Other water supply problems Damaged or broken lateral Damaged or broken submain Sudden pressure decrease at filter output Damaged or broken mainline ePressure regulator failure Water supply failure check flow rates Gradual pressure increase at filter output Emitter plugging i i Other flow restriction check flow rates Stuck control valve Other flow restriction check flow rates Sudden pressure decrease at submain Damaged or broken lateral check flow rates Sudden pressure increase at filter output RO DRIP USERS GUIDE MANAGEMENT Pressure gauges Pressure gauges or ports for a pressure gauge should be installed on the mainline both before and after the filters The pressure gauge or port after the filters should be located near the mainline flow meter since flow and pressure changes can work together to reveal a variety of potential problems Additional information can be obtained by installing a pressure gauge at each submain riser As with flow meters all pressure gauges should be read and recorded for the new system and on a regular basis thereafter Table 5 6 previous page shows some of the problems you can diagnose by keeping track of system pressures Act on any of these problems immediately to avoid serious crop damage Note Table 5 6 is intended as an example of some problems that can be diagnosed through regu
30. flushing is necessary the system should be designed so that the ends of the laterals are accessible Consider using end caps or flushing manifolds In systems where flushing is necessary the capacity of the upstream components is often determined by the flushing requirement alone It is recommended to maintain a minimum flushing velocity of 1 foot per second in the laterals which requires flow rates at the end of laterals to be at least 1 GPM 3 8 LPM in standard 5 8 in 16 mm drip tape or 2 GPM 7 6 LPM for 7 8 in 22 mm drip tape Substantially higher flow rates at the beginning of the laterals are required to achieve these flow rates at the end of the laterals CROP CHOICE The crops you grow will have a great effect on system design and cultural practices Any and all crops can be grown under drip irrigation but your choice of crops and their planting method direct seeded or transplanted will have an important impact on your drip system design An important question about your crops is whether they will be direct seeded or transplanted The germination of seeds places special requirements on your drip system design and management If these requirements are not met sprinklers will be required for germination and initial plant RO DRIP USERS GUIDE 25 PLANNING CAUTION all personnel who use or otherwise come in contact with fertilizers and chemicals should be thoroughly trained and qualified in the safe and effecti
31. for disposal simply pull it from the field and bale it together As described in the previous section make the bales as tight as possible and tie them together with string or drip tape for easy disposal MECHANIZED RETRIEVAL The main tool used for mechanized drip tape extraction is the retrieval head The retrieval head consists of a driven shaft onto which the spool is mounted and a guide to bring the drip tape to the spool fig 6 2 A means of tension control is usually provided to avoid damage to the tape during momentary hang ups or during rapid speed changes of the tractor Some retrieval heads incorporate a level wind mechanism that places the drip tape evenly on the spool as it rolls These mechanisms make the roll more compact and easy to re use Retrieval heads and complete Figure 6 2 Retrieval Head Courtesy of Andros Engineering retrieval systems are available from several RO DRIP USERS GUIDE 6 3 RETRIEVAL suppliers Retrieval heads can either be mounted over the row on a tractor tool bar or end of row where the head is stationary and the drip tape is pulled out of the row from one end after it has been picked up and placed on top of the crop Surface and Shallow Subsurface Drip Systems Surface and shallow subsurface less than 3 in deep laterals are the simplest to remove either for re use or disposal When laterals are placed on the surface either end of row or over the row techniques can be use
32. given emitter spacing less susceptible to emitter plugging than low flow products improved infiltration on heavy soils longer lateral run lengths are possible more susceptible to emitter plugging higher flushing requirements Low Flow Table 3 5 Standard Flow and Low Flow RO DRIP Products EMITTER SPACING STANDARD FLOW LOW FLOW US i 40 GPH 100 ft 20 GPH 100 ft Metric 497 LPH 100m 248 LPH 100m US 24 GPH 100 ft 15 GPH 100 ft Metric 298 LPH 100m 186 LPH 100m US 20 GPH 100 ft 10 GPH 100 ft Metric 248 LPH 100m 124 LPH 100m If your system requires a higher flow rate than your water supply can provide it will not work It will be necessary to divide your field into smaller zones that can be irrigated indepen dently or reduce the number of acres you are irrigating Use the following formula to calculate the total flow rate Q each zone of the system will require of your water supply or use the tables in appendix E tape flow rate GPH 100 x feet of tape tape flow rate LPH 100m x meters of tape i 6000 6000 If US units are used in the above formula Q will be in gallons per minute If metric units are used Q will be given in liters per minute Calculate the application rate AR of your system as follows or use the tables in appendix E RO DRIP USERS GUIDE DESIGN tape flow rate GPH 100 tape flow rate LPH 100m 62 x lateral spacing feet 100 x lateral
33. ig eee eee het cos peppers Primary filtration screen filter Location Pennsylvania USA Secondary filtration none Field size 25 acres 10 ha SUDMAING 344430 2 A 304 9924 4445 2 layflat Plants per acre 12 000 30 000 per ha Mulch oi yanasa ss Dee 44 black plastic SEASON pitas arses ee E aao sea summer f Planting method transplant Management Operation Soil type ce ec sees terete ees siltyloam Irrigation frequency 1 2 times per week Maximum ET 0 30 in 7 5 mm per day Irrigation duration 4 6 hours Water Source deep well Chemigation yes Ground cover Plastic mulch Fertigation yes Crops rotated with cabbage corn tomato Line FUSE RE EE yes Time to maturity 60days Filter back flushing yes Average yield 22 5 tons acre 50 tons ha Duration of tape installation 120 days Drip Tape RO DRIP 8 12 24 8 mil 12 in spacing 15 GPH per 100 ft 5 8 in diameter 200 mm 30 cm spacing 186 LPH per 100 m 16 mm diameter RO DRIP USERS GUIDE COEFFICIENT OF VARIATION AND EMITTER DISCHARGE EXPONENT The Roberts Difference RO DRIP is manufactured with an advanced high precision process which results in an emitter coeffi cient of variation of 0 03 or lower This translates to better di
34. is important to thoroughly flush the system check for leaks or breaks and ensure that all components are working properly Make sure you have gone through all of the following steps before you use your drip system to irrigate your field Open mainline flushing valves with submain valves closed until discharge water runs clear for 5 minutes Close the mainline flushing valves In large systems dye can be added in the filter station when the dye is no longer visible at the end of the line flushing is complete Connect laterals to the submains without terminating the ends For each submain open the control valve until the discharge water at the end of each lateral runs clear If the capacity of your water supply is not high enough to flush all laterals simultaneously it may be necessary to terminate some of the laterals so that you can flush only a few laterals at a time Close the submain control valves Close the laterals or connect the ends of the laterals to the flushing manifold if used Operate the system until it is fully pressurized and all air is discharged Check the system for leaks and repair them if necessary Re flush after all leaks are repaired Check all pressure gauges and adjust pressure regulators or regulating valves if necessary Check for proper operation of all system components pumps controllers valves air vents pressure regulators pressure gauges flow meters filters and chemical injectors
35. of drip fertigation NOTE Fertilizers containing calcium should be flushed from all tanks pumps filters and tubing prior to injecting any phosphorus urea ammonium nitrate urea sulfuric fertilizer or any sulfate form of fertilizer to avoid precipitation which can cause severe emitter plugging Always test the compatibility of fertilizers with each other and with your irrigation water before mixing them in your system Frequency of Applications Drip irrigation allows fertilizer to be applied as frequently as your plants need even daily if necessary This flexibility allows you to quickly make adjustments to your fertigation program to respond to changes in your plant needs and use expensive fertilizers as efficiently as possible When to Fertilize Inject fertilizer during the latter part of the irrigation cycle to reduce the possibility of leaching some of it past the root zone However be sure to operate the system long enough to completely purge fertilizer from the laterals to avoid algae and bacteria growth Plugging is likely to occur if algae and bacteria are allowed to grow and feed on the residual fertilizer left in the laterals The travel time required to transport chemicals to the end of a long over 1000 feet drip lateral can be up to 60 minutes depending on slope and flow rate Travel times through mainlines and submains must also be considered Several software packages are available which calculate travel time within lateral
36. of light rain deep subsurface drip systems for salt sensitive crops must be left running to pre vent the rain from leaching salts into the root zone If rain is heavy enough salts will be leached below the root zone where they will not cause problems NOTE Where salt buildup is a problem a surface or shallow subsurface placement will give the best results Do not move drip laterals after water application has started on salt sensitive crops Moving the laterals will cause the salt buildup to move If the salt buildup moves into the root zone it will stress or even kill plants Also do not allow the soil in the root zone to dry between irrigation cycles This can result in reverse movement of soil water and transfer salt from the perimeter back into the rooted area of the soil Salt Leaching To minimize salt buildup in the root zone keep the wetted area at or near field capacity at all times For optimal salinity control maintain a nearly continuous slow downward movement of water and salts This requires more water than is necessary to maintain field capacity The addi tional water added to leach salts away from the root zone is commonly referred to as the leaching requirement and in problem areas can be as much as 10 20 of the total application rate Place drip laterals as close as possible to salt sensitive plants to continuously leach salts outward from the root zone Monitor the soil salinity throughout the season to help maintain
37. performance of your system depends on consistent control of water pressure Regardless of how well your system is designed or how well your drip tape is manufactured operating pressures must remain at design specifications to maintain the desired distribution uniformity Changes in pressure can indicate a variety of problems A pressure drop may indicate a leak a component or line break a blocked filter or a malfunctioning pump A pressure increase usually indicates a block in the filters valves or lines Install pressure gauges on the mainline both before and after the filters You can obtain additional information by installing a pressure gauge directly downstream of each pressure regulator to indicate the actual pressure supplied to the submains As with flow meters read all pressure gauges and record the information when the system is new and on a regular basis during operation CHEMIGATION FERTIGATION Controlled injection of chemicals and fertilizers may be the most important benefit of your drip irrigation system Substances commonly injected into drip systems include chlorine acids fungicides herbicides pesticides and fertilizers This section describes the design aspects of chemical injection Use of your injection system for treating your irrigation water and fertilizing your crops is described in MANAGEMENT Maintenance Water Treatment and MANAGE MENT Fertigation Precision application of high quality fertilizers is especially i
38. poor quality water 800 to 4000 ppm total dissolved salts can be used until maturity After harvest the salt must be leached from the soil before planting the next crop If there is inadequate raintall to accomplish leaching a heavy flood or sprinkler irrigation will be required When using salty water lay drip tape on or near the surface to keep buildup away from the plants With higher quality water the laterals can be buried up to 18 in 46 cm deep and on heavy soil can be spaced up to 80 in 203 cm apart On sandy soils space the laterals 40 in 102 cm apart When using a deep buried drip system it is necessary to use a supplemental irrigation system to germinate Cotton should not be grown for more than 2 to 3 years on the same land without rotating in another crop such as wheat sugar beets process tomatoes or melons Drip irrigation can increase yields with all crops and since you can use the same drip system with successive crops a well planned system will allow you to offset the initial installation cost EXAMPLE Cotton Central Texas USA o 807 Operation Auxiliary Equipment Crop sania sentis Pel upland cotton Primary filtration sand media Location Central Texas USA Secondary filtration none Field size 100 acres 40 ha SUDMAING ee das eres ade 8644444 PVC Plants per acre 19 000 47 000 per ha Mulch irasat Dia ie a e none SEASON o zz h
39. root zone before it increases to a level that seriously affects yield Symptoms of excess salinity depend on the type of crop and the types of salts involved Mild salinity problems are frequently overlooked because the plant size reduction and change in color are uniform across the field Excess salinity initially causes a subtle change in color As salinity stress increases stunting becomes apparent and leaves are eventually burned at the tip and around the edges It is important to recognize that yield loss from excess salinity occurs well before the symptoms are visible in your plants Patterns of Salt Buildup in the Soil Most salts are readily soluble and move with water in the soil The salt content of the root zone varies with depth and distance from the point in the soil where water is applied applica tion point Salinity near the application point of irrigation water is usually low Salt builds up at the outer edges of the wetted area Figure 5 5 shows salt patterns caused by different lateral placements If the drip lateral is installed near the soil surface and the wetted area brings the soil near the surface and plant row to above field capacity then the salt layer will move away from the seed line or plants If the lateral is placed deep enough so that the wetted Figure 5 5 Salt Patterns RO DRIP USERS GUIDE MANAGEMENT area does not reach the surface salt can build up just under the surface of the soil During periods
40. uniformity in many cases In addition the submain connection to the mainline fig 3 7 may include a control valve an air relief valve and if necessary a secondary screen filter DIVIDING YOUR FIELD INTO INDEPENDENT ZONES Most large drip irrigation systems are comprised of several zones that can be independently scheduled Each zone typically has one or more submains and a control valve that allows it to be turned on and off Automatic irrigation controllers are helpful if several zones are implemented each with a different schedule More than one independent zone may be required if one of the following situations apply The capacity of your water supply is not sufficient to irrigate your entire field at the flow rate and lateral Spacing specified in your design see the example in Selection of Flow Rate Fields are staggered for different planting and harvesting dates Several different crops are being irrigated with different water requirements RO DRIP USERS GUIDE 3 15 3 16 DESIGN e Topography varies throughout your operation Drainage or soil texture vary throughout your operation Maximum Zone Size The maximum size of any one zone is determined by the capacity of your water supply lateral spacing in feet x water supply capacity GPM N acres 7 26 x tape flow rate GPH 100 or lateral spacing in meters x water supply capacity LPM 1 67 x tape flow rate LPH 100 m N acres
41. valves sometimes used in smaller systems Gate valves should only be used for for on off operation and not to partially restrict flow since the valve may wear while partially open and may not seat properly when closed Air vent vacuum relief valve Air that accumulates in mainlines and submains can restrict flow and lead to damage from water hammer Vacuum conditions which can occur in drip laterals when the system is shut down can cause contaminants to be sucked into the emitters and lead to plugging In addition the vacuum that forms downstream of control valves when they are suddenly closed can dam age pipes or the valves Install air vacuum relief valves e At all high points on mainlines and submains e At the ends of mainlines and submains e Downstream of all control valves e Upstream of pump check valves Check valve Check valves only allow flow in one direction If chemical injection is used a check valve should be installed at the output of the chemical holding tank to prevent irrigation water from flowing into the tank Check valves are also installed downstream of pumps to prevent water from flowing in the wrong direction when the pump is turned off Backflow prevention valve A backflow prevention valve prevents water from flowing back into the supply from the irrigation system There are several types of backflow prevention valves that use different mechanisms to operate Backflow prevention valves prevent chemicals and other c
42. 24 GPH per 100 ft XX 24 17 24 inch emitter spacing 17 GPH per 100 ft and XX 12 24 XL 12 inch emitter spacing 24 GPH per 100 ft 7 8 in ID The XX term denotes the wall thickness and can be 5 8 10 13 or 15 mil For a complete set of performance charts for all RO DRIP products see the Roberts Irrigation Products publication RO DRIP PERFORMANCE DATA D 1 D 2 SAMPLE RO DRIP PERFORMANCE CHARTS 1 0 1 Cv 0 03 x EU Table D 1 Sample Performance Charts Maximum Run Length feet RO DRIP XX 12 24 q 0 40 0 52 k 018396 Inlet Pressure psi 6 8 10 MP 1078 1088 1088 1081 936 941 939 930 735 754 750 RO DRIP XX 24 17 Cv 0 03 x 0 52 q 0 28 Inlet Pressure psi 6 8 10 k 115311 12 RO DRIP XX 12 24 XL Cv 0 03 x 0 52 q 0 40 k 081396 Inlet Pressure psi FU 6 8 10 12 1896 1928 1939 1632 1664 1677 1240 1306 1333 Cv coefficient of variation q discharge rate GPM 100 x emitter exponent k flow constant required filtration 140 mesh RO DRIP USERS GUIDE LENGTH APPLICATION RATES AND FLOW RATES The tables in this appendix summarize the results of the equations given in DESIGN Lateral Design for several drip tape flow rates and lateral spacings Lateral spacings and flow rates must be specified for an application rate sufficient to meet irrigation requirements during peak ET Tables El and E3 without exceeding the capacity of the
43. 2c d Connecting a Glued Fitting Figure 4 13 Directly Connecting a Transfer Tube to a PVC Submain to a PVC Submain Connecting to Polyethylene Hose Submains There are 2 basic methods for connecting a drip lateral to a poly hose submain using a direct transfer tube or using a fitting Fittings are available that directly connect polyethylene hose submains to the following Drip tape using a lock sleeve fitting Transfer tubing using an external compression fitting Transfer tubing using an internal barb Figure 4 14 shows several fittings available for connecting laterals to poly hose submains Figure 4 14 Common Fittings for Poly Hose Submains RO DRIP USERS GUIDE INSTALLATION AND STARTUP Create a hole in the poly hose submain that is slightly smaller than the outside diameter OD of the transfer tube or barb fitting fig 4 15 Use the procedure shown in figure 4 16 to connect a fitting to a poly hose submain or figure 4 17 to directly connect a transfer tube See Connecting a Transfer Tube to a Lateral below for instructions on connecting the transfer tube to a drip tape lateral once it has been connected to the submain Figure 4 15 Creating a Hole in a Poly Hose Submain Figure 4 16 Connecting a Fitting to a Poly Hose Submain Figure 4 17 Connecting a Transfer Tube to a Poly Hose Submain Connecting to Layflat Hose Submains There are 2 basic methods for connecting a drip lateral to a layflat hose submain
44. 8 2 08 1 76 1 55 140 7 143 3 57 2 13 1 78 1 51 133 160 6 250 312 1 86 1 56 1 32 1 16 180 00 I 210 I 230 1 31 1 11 0 99 2 i 1 25 1 06 0 93 j 0 96 0 85 0 92 0 81 4 167 i 0 88 0 78 2 94 1 72 1 47 1 24 1 09 3 1 66 1 38 1 17 1 03 RO DRIP USERS GUIDE E 3 ENGINEERING CONVERSION FACTORS F2 ENGINEERING CONVERSION FACTORS APPENDIX F ENGINEERING CONVERSION FACTORS LENGTH To Multiply by To Convert To inches 63 360 kilometers meters Multiply by 1 000 feet 5 280 kilometers feet yards 1 760 kilometers yards 3 280 8 1 093 6 nautical miles 0 87 kilometers miles meters 1 609 34 kilometers nautical miles 0 6214 0 54 kilometers 1 609 meters centimeters meters 0 3048 meters inches 100 39 37 centimeters 30 48 meters feet centimeters 2 54 meters yards 3 281 1 094 millimeters 25 4 centimeters inches mils 1 000 millimeters inches 0 3937 0 03937 microns 25 4 millimeters microns microns mils APPENDIX F ENGINEERING CONVERSION FACTORS AREA To Convert To Multiply by To Convert To sq miles acres 640 sq kilometers hectares 1 000 0 03937 Multiply by 100 sq miles hectares 259 sq kilometers acres 247 1 sq miles sq kilometers 2 59 sq kilometers sq miles 0 3861 acres sq feet 43560 hectares sq meters 10 000 acres sq yards 4840 hectares acres 2 471 acr
45. 8 Cubic Centime Ounces 0 0338 ons Liters 3 785 Cubic Centimel Tablespoons 0 067 ons Quarts Cubic Centime Fluid Ounces ons Pints Cubic Millimeters Cubic Centimeters ons Ounces Quarts Gallons Quarts Pints Quarts Liters Quarts Cubic Centimeters Quarts Cubic Inches Quarts Pints Pints Gallons Pints Quarts Pints Ounces Pints Liters Pints Cubic Centimeters Pints Cubic Inches Cups Liters Cubic Inches Cubic Feet 0 00058 Cubic Inches Cubic Yards 2 14x10 5 Cubic Inches Cubic Centimeters Cubic Inches Gallons Cubic Inches Liters Cubic Inches Quarts Cubic Inches Pints Fluid Ounces US Gallons Fluid Ounces Pints Fluid Ounces Cubic Centimeters Tablespoons Cubic Centimeters RO DRIP USERS GUIDE F 4 ENGINEERING CONVERSION FACTORS APPENDIX F ENGINEERING CONVERSION FACTORS WEIGHT AND MASS To Convert To Multiply by To Convert To Multiply by Ounces Grams 28 35 Grams Ounces 0 0353 Ounces Pounds 0 0625 Grams Pounds 0 0022 Ounces Kilograms 0 0284 Grams Kilograms 0 001 Pounds Grams 453 6 Kilograms Grams 1000 Pounds Ounces 16 Kilograms Ounces 35 21 Pounds Kilograms 0 454 Kilograms Pounds 2 205 Pounds Tons short 0 0005 Kilograms Tons 0 0011 Pounds Tons long 0 00045 Kilograms Metric Tons 0 001 Pounds Metric Tons 0 000454 Metric Tons Kilograms 1000 Tons short
46. Control of the wetted area Water conservation Protection of fruit from soil moisture Control of weeds pests and erosion Improved yields Control of production timing Prevention of nutrient leaching due Improved processing of nutrients by to rainfall beneficial microbes If you plan to use clear plastic mulch or crop tunnels your system design should specify buried drip tape since the heat trapped by these plastics may cause wandering of the tape as a result of increased expansion and contraction Note that plastic mulch is not optimal or even practical for all crops see appendix B for information on specific crops Figure 2 1 Plastic Mulch RO DRIP USERS GUIDE 2 7 DESIGN Drip irrigation delivers the highest efficiency and uniformity of any commonly used form of irrigation This can directly result in reduced consumption of water chemicals and fertilizer High uniformity in combination with the low application rates of drip irrigation makes possible the precise control of soil water content at the root zone which leads to more effective application of nutrients better salinity control and increased yields Only by designing installing and maintaining an efficient system can you achieve all of the benefits of drip irrigation Selecting the right drip tape product properly sizing supply mani folds and selecting appropriate filtration components are all necessary to maximize efficiency and to meet the irriga
47. Elf Atochem North America CAUTION Never inject acid into aluminum pipe Injection Rates One of the primary benefits of drip fertigation over other fertilizer application methods is the accurate control of application rate In addition the effectiveness of chlorine acid and other chemicals depends heavily on concentration As a result it is important to design an injection system that allows good control over injection rates Pressure differential tanks in particular are not recommended where accurate control of injection rate is required Backflow Prevention If you inject fertilizer or chemicals into your system it is essential and in some cases is required by law to install a backflow prevention device upstream of the injection point Depending on local your regulations this may require a pressure reduced backflow preventer or a double check valve assembly RO DRIP USERS GUIDE 3 21 3 22 DESIGN venturi gravity tank lt pressure differential metering Pump Figure 3 12 Common Injector Types Table 3 12 Common Injector Equipment and Their Features Batch or Pressure Differential Tank Gravity Tank Venturi Device Metering Pump RO DRIP USERS GUIDE A pressure differential caused by a valve or other restriction is used to force water into a tank containing the chemical The chemical then mixes with the water exits the tan
48. LLANEOUS Boron B ppm 0 2 Acidity pH 6 0 8 5 Sodium Adsorption Ratio 0 15 l dS m deciSiemen per meter equivalent to mmho cm mell milliequivalent per liter 2 NO3 N is nitrogen in the form of nitrate NH4 N is nitrogen in the form of ammonia Both may be reported as N 3 SAR is calculated from the reported Na Ca and Mg SAR xa F el 2 RO DRIP USERS GUIDE UNDERSTANDING WATER QUALITY REPORT Table A 2 Guidelines to Interpret Your Water Quality Report Water Quality Problem SALINITY affects plants ability to take up water Restriction on Water Use Severe ECw dS m or TDS ppm INFI if SARa 0 3 SARa 3 6 SARa 6 12 SARa 12 20 SARa 20 40 Sodium SAR Sodium mell Chloride me l Boron ppm ECw lt 0 7 TDS lt 450 ECw gt 0 7 ECw gt 1 2 ECw gt 1 9 ECw gt 2 9 ECw gt 5 0 SAR lt 3 me l lt 3 me l lt 4 ppm lt 0 7 OTHER EFFECTS affects sensitive crops Nitrogen NO3 N ppm Bicarbonate HCO3 mell ppm lt 5 mell lt 1 5 PH Normal Range 6 5 8 5 LTRATION affects rate water enters soil use SAR and ION TOXICITY affects sensitive crops 0 7 lt ECy lt 3 0 450 lt TDS lt 2000 0 2 lt ECw lt 0 7 0 3 lt ECy lt 1 2 0 5 lt ECw lt 1 9 1 3 lt ECy lt 2 9 2 9 lt ECw lt 5 0 3 lt SAR lt 9 3 lt mell lt 9 4 lt mell lt 10 0 7 lt ppm lt 3 5 lt ppm lt 30 1 5 lt me l l
49. MPLE Tomatoes Coastal Virginia USA i 72 Operation Auxiliary Equipment Gio etat addicte sab ee tomatoes Primary filtration sand media Location Coastal Virginia USA Secondary filtration screen Fieldsize 250 acres 100 ha OUDMAING 4440433354224496 aa PVC Plants per acre 3630 8970 per ha Mulch plastic 60 x 1 25 mil CASON 2 DE situ sitat ei Spring Fall f Planting method transplanted Management Operation Soil type arrera sandyloam Irrigation frequency daily Maximum ET 0 3 in 75 mm per day Irrigation duration 1 3 hours Water Source surface water pond Chemigatiort saan aaa aaa 4 yes Groundcover DONE Rertigatl n cons aa tas as yes Crops rotated with soybeans Tineflushing yes Time to maturity 80 90 days Filter back flushing automatic Average yield 20 tons acre 45 tons ha Duration of tape installation 5 months Drip Tape RO DRIP 8 12 24 8 mil 12 in spacing 24 GPH per 100 ft 5 8 in diameter 200 mm 30 cm spacing 298 LPH per 100 m 16 mm diameter RO DRIP USERS GUIDE B 9 CROP PRODUCTION Potatoes Potato production requires good water penetration and aeration The soil must also be worked properly for correct tuber formation and growth Potatoes
50. S THE EXPERTS If you are like most growers you have vast experience with traditional sprinkler or furrow irrigation practices You recognize the value of this accumulated expertise and probably would not think of irrigating your fields without applying that knowledge to get the best result If you are new to drip irrigation you can be sure there is a great deal to learn from quick tips and techniques to fundamental changes in your procedures Until you reach a comfortable level of expertise in drip irrigation it makes sense to get in touch with someone who can share their expertise with you Specifically you should be prepared to contact qualified experts in hydraulic engineering filtration chemical treatment pest control and installation What you learn from these experts in one season will pay off for years to come In a recent survey of experienced growers all confirmed the value of becoming fully informed especially by consulting experts before initiating their own drip irrigation program MANAGING NEW CULTURAL PRACTICES Drip irrigation allows precision response to changes in crop need environmental conditions RO DRIP USERS GUIDE INTRODUCTION and even market timing All of these benefits require a well functioning system Unlike tradi tional irrigation methods that use fewer larger applications of water successful drip irrigation is based on many small applications This requires a new way of thinking collecting and reco
51. Second 6 39x10 Liters per Second Cubic Feet per Second 0 0353 Gallons per Minute Liters per Second 0 0631 Liters per Second Gallons per Minute 15 85 Gallons per Minute Cubic Feet per Second 0 00223 Gallons per Minute Acre Inches per 24 Hours 0 053 Gallons per Second Liters per Minute 0 0631 British Gallons per Minute Liters per Minute 0 0757 RO DRIP USERS GUIDE ENGINEERING CONVERSION FACTORS APPENDIX F ENGINEERING CONVERSION FACTORS VELOCITY Multiply Multiply Miles per Hour Feet per Second 1 467 Kilometers per Hour Feet per Minute 54 68 iles per Hour Feet per Minute 88 Kilometers per Hour Feet per Second 0 91 iles per Hour Meters per Second 0447 Kilometers per Hour Meters per Second 0 28 iles per Hour Centimeters per Second 44 7 Kilometers per Minute Meters per Second 16 67 iles per Hour Meters per Minute 27 0 Meters per Minute Miles per Hour 0 037 iles per Minute Feet per Minute 5280 Meters per Second Kilometers per Hour 3 6 iles per Minute Meters per Second 26 82 Meters per Second Kilometers per Minute 0 06 iles per Minute Centimeters per Second 2682 Meters per Second Miles per Hour 2 237 et per Minute Kilometers per Hour 0 0183 Meters per Second Miles per Minute 0 037 Feet per Minute Meters per Second 0 00508 Meters per Second Feet per Minute 196 8 Feet per Minute Miles per Hour 0 0114 Meters per
52. TURES lower cost than 7 8 in 22 mm diameter products run lengths are sufficient for most field layouts larger variety of emitter spacings and flow rates are available Standard Diameter 5 8 in 16 mm every long lateral runs with high uniformity are possible eless problems with high water application at head of field on heavier soils allows use of fewer submains possibly resulting in cost savings fewer submains may also result in fewer tractor turns higher cost than standard diameter fittings and other components may cost more than with standard diameter Large Diameter 7 8 in 22 mm RO DRIP USERS GUIDE DESIGN Table 3 7 provides background on the selection of tape diameter Actual design decisions may require run length information from performance charts and price information from your irriga tion dealer See the Roberts Irrigation Products publication RO DRIP PERFORMANCE SPECIFI CATIONS MAINLINES AND SUBMAINS Field Uniformity The previous section explained how to use performance charts to select a drip tape prod uct and run length that meet your uniformity goals along the length of each lateral It is Mente equally important to select mainlines sub i mains and other components to ensure that the supply pressures to all of the laterals are consistent so the distribution uniformity over the entire field will meet your goals O lt Filter station Drip laterals lt
53. a asnapa amassss May planting f Planting method direct seeded Management Operation Soil type cauen inc eee ee silt clay loam Irrigation frequency 1 2 times per week Maximum ET 0 35 in 9 mm per day Irrigation duration 4 hours Water Source saa ayama aaa well Chemigation yes Ground cover winter wheat Fertigation yes Crops rotated with iets Yasta stss su none Line flushing 3 times per year Time to maturity Filter back flushing automatic Average yield 2 25 bales acre Duration of tape installation multi year Drip Tape RO DRIP 15 12 15 XL 15 mil 12 in spacing 15 GPH per 100 ft 7 8 in diameter 381 mm 30 cm spacing 186 LPH per 100 m 22 mm diameter RO DRIP USERS GUIDE B 11 B 12 CROP PRODUCTION Corn Corn is typically seeded on 30 in 76 cm row spacings with 6 to 10 in 15 to 25 cm in row spacing One drip lateral is placed between every other pair of rows resulting in a 60 in spacing between laterals Twelve inch emitter spacings are common at either 15 or 24 GPH per 100 ft Since RO DRIP XL drip tape can deliver good uniformity on runs up to _ mile long it is often used in grain applications where large filed sizes are common Drip irrigation is becoming a method of choice in applications such as corn which have traditionally been
54. a valve can be opened or an end cap can be removed to flush them all simultaneously If flushing manifolds are used their diameters must be large enough to allow sufficient flow velocity from the ends of the laterals In addition the connection from each lateral to the flushing manifold should not significantly restrict flow To effectively remove sediment the flush ing velocity should be at least 1 ft sec at the end of each lateral This translates to approxi mately 1 GPM 3 8 LPM for a 5 8 in 16 mm lateral or 2 GPM 7 6 LPM for a 7 8 in 22 mm lateral Depending on run length this may require 2 to 3 GPM 7 6 to 11 LPM from the supply manifold to flush a single 5 8 in lateral or 3 to 5 GPM 11 to 19 LPM for a 7 8 in lateral When designing a manifold to Figure 3 6 Design for Lateral Flushing RO DRIP USERS GUIDE 3 13 DESIGN Table 3 8 Types of Submains Material Description Advantages Disadvantages Rigid PVC pipe eLong life if buried Degrades if exposed to sun light should be buried More difficult to work with than PE hose or layflat Not easily portable Flexible polyethylene hose eLong life 3 5 yrs in above Requires more storage space with round or or below ground applica than vinyl layflat oval shaped cross section tions Thermal expansion and con Easy to install simply traction can cause movement unroll from coil Can flatten in a buried trench Easy to attach l
55. al components Inorganic matter e Organic matter Chemical components Dissolved minerals e Minor elements Salt Acidity RO DRIP USERS GUIDE PLANNING Since all of these factors interact in complex ways to affect the operation of your drip system consult a water quality specialist and an irrigation engineer when designing your drip system Also because water sources can change with time perform water quality tests periodically and make adjustments as necessary See appendix A for tables to assist you in understanding your water quality report Inorganic Matter Inorganic matter found in water sources includes sand pipe scaling and other large particles all of which can lead to plugged emitters and other damage to your system Since these particles are usually heavier than water they can often be removed using a centrifugal sand separator see DESIGN Filtration Smaller inorganic particles such as silt and clay can become cemented together by bacteria and algae which results in a slimy buildup that can clog emitters Since these smaller particles are more difficult to remove media filters and or settling basins may be required to protect your system Organic Matter Organic matter found in water sources includes algae slime plants and particles from other living organisms While some of these can be removed by standard filtration equipment chemical treatment of the water and lines is usually required for more comple
56. alers and agronomists is recommended This guide is specifically written for irrigation with drip tape thin walled collapsible emitting hose While many of the concepts are applicable to other forms of drip irrigation such as hard wall hose with inserted or in line emitters this guide does not specifically address such products All of the steps involved in assembling and managing a successful drip irrigation system are covered in the following sections Planning Design Installation and Startup Management and Retrieval We recommend that you read the guide completely before beginning your drip irrigation program At a minimum review the following summary of Important Cautions and Notes Also consider reviewing the Key Concepts listed at the beginning of each section IMPORTANT CAUTIONS AND NOTES Observe the following important cautions and notes when designing installing and managing your drip irrigation system e Carefully design and engineer all parts of your drip irrigation system before installation and use Consult specialists in irrigation water quality pest control agrochemicals and other areas as necessary Always use proper filtration for your water source Inadequate filtration or filter maintenance may severely damage your drip irrigation system Where ground pests are a potential problem always implement pest controls before installing drip tape e Do not step on drip tape or drag it across the soil surface Ensure that
57. amounts of water are applied frequently often daily Regularly monitor pressures flow rates soil moisture and other factors to take full advantage of the high level of control that drip irrigation offers The central goal of a drip irrigation maintenance program is to keep the emitters clean so they will continue to deliver water and nutrients uniformly to your plants The Roberts Difference RO DRIP and RO DRIP XL provide the most reliable cost effective solution for subsurface and above ground irrigation 5 1 5 2 MANAGEMENT SCHEDULING The goal of drip irrigation scheduling is to select an irrigation duration and frequency that results in a properly sized wetted area around plants and keeps the soil in the root zone at or near field capacity The right schedule for your system depends on your specific crop requirements soil texture field preparation and weather conditions Adjustments throughout the season based on monitoring of field conditions allow you to fine tune the irrigation schedule to the needs of your crop NOTE Deficit irrigation can be used to increase the soluble solid content of fruits or vegetables by deliberately maintaining soil moisture below field capacity This is usually done at the end of the growing season shortly before harvest and is common with grapes sugar cane tomatoes cotton and several other crops Precise control of application rates make drip irrigation ideally
58. anced emitter design and smooth inside walls of RO DRIP products allow long lateral runs with high uniformity RO DRIP performance charts are available in the Roberts Irrigation Products publication RO DRIP PERFORMANCE SPECIFICATIONS 3 4 DESIGN Plugging resistance Drip tape can become non uniform to a point where it is completely debilitated in the midst of a growing season if emitters become plugged This can result from any of the following e Organic or inorganic sediment in the irrigation water A vacuum condition inside of the drip tape causing dirt to siphon back in through the outlet e Root intrusion e Mineral buildup in the flow channel or at the outlet The primary features of an emitter that determine its likelihood of plugging are the cross sectional area of its flow channel and the amount of turbulence created within the flow channel A large cross section gives plenty of room for contaminants to pass through without accumulating into clogs A highly turbulent channel keeps dirt particles suspended as they move through the emitter Other emitter features also play important rolls in plugging resistance Some drip tape products have emitter outlets that resist root intrusion The design of the emitter inlet can also affect clog resistance Finally some emitters provide mechanisms that help to remove clogs if they should occur DRIP LATERAL DESIGN To design your drip laterals you need to specify the following
59. any of the same applications as media filters Used for pre filtration at pump intake Pre filtration to remove silt or other inorganic particles Fine sand particles with in pairs of closed tanks create a three dimen sional filtering surface Removes algae slime and fine suspended solids Filters are back flushed one at a time while remaining units continue filtration Fine meshed screen enclosed in a pressurized tank traps organic and inorganic particulate Centrifugal action creates a vortex that pushes away particulate that is heav ier than water Removes well casing scale sand and other inorganic par ticulate Water falls on a screen separator which catch es particulate Particulate is washed into a collection tank Filters water through microscopic grooves on densely packed discs Relatively coarse screen traps debris Allows suspended parti cles to settle Removes high quantities of silt and clay particles Also provides aeration to remove some dissolved solids and iron suspension eFiltration to 74 microns 200 mesh Sizes 12 48 in 30 120 cm Use at least 3 tanks if possible to avoid back flushing problems Available screen mesh 50 to 200 300 to 74 micron Available sizes 0 75 10 in 1 8 25 cm Removes particles heav ier than water down to 74 microns 200 mesh Works with 5 7 psi pressure loss Available from 100 200 mesh Avai
60. ape after it is removed from the field If you plan to dispose of drip tape it should be compacted and baled as tightly as possible The retrieval head is the main tool used for mechanized drip tape retrieval e The two common retrieval methods are over the row retrieval using a tractor and end of row retrieval using a fixed retrieval head e The most common problem encountered during retrieval is damage to the drip tape from stretching Ensure tape is free of entanglements and water has been removed If possible perform retrieval in the morning before the sun heats up the drip tape 6 1 6 2 RETRIEVAL DISPOSAL VS RE USE The following options are available at the end of the growing season e Retrieval and disposal of drip tape Retrieval and re use of drip tape e Leaving drip tape installed for the next season Retrieval and disposal is currently the most common method used although the other options are becoming more popular The replacement cost of drip laterals in combination with ever increasing disposal costs weigh in favor of using laterals for more than one season Multiple year installations which are not retrieved and re installed after each season are usually buried deep below the surface 6 18 in so cultural operations can be performed without causing damage Table 6 1 summarizes the advantages and disadvantages of each option Table 6 1 Disposal vs Re use of laterals Method Advantages Disad
61. aterals and fittings Portable Polyethylene Hose Collapsible vinyl hose which Very compact for Shorter life than poly hose or inflates under water pres shipping and storage buried PVC sure Relatively long life in Often moves due to above ground internal water velocit Vinyl Layflat applications 2 4 yrs i Easy to install simply unroll from coil Portable flush several laterals simultaneously it is important to ensure that the capacity of your water supply will not be exceeded If it is the flow requirements during flushing can be reduced by using several smaller flushing manifolds at the end of the field which can be opened individually Submains on Uneven Terrain When drip laterals are in a level orientation across a steep slope the submains run up or down the slope Pressure variations will occur within the submains if they are long and or the Table 3 9 Minimizing the Effects of Submain Pressure Variations If submains are short the elevation change along each is less than 5 feet 1 5 m and a pres Short submains sure regulator is installed at the beginning of each submain pressure variations will be within acceptable limits A flow restriction is installed on the submain at each 5 foot 1 5 m change in elevation The flow restriction can be an in line valve on a PVC or poly hose submain or a clamp on a layflat Flow restrictions submain This method requires some trial and error to adjust the r
62. ating or transplanting soil texture and crop selection Choice of flow rate depends on water availability ET requirements length of drip tape laterals soil texture and crop selection Standard drip tape is 0 625 in diame ter Larger diameter drip tape products allow longer lateral runs but are more costly 1000 ft 305 m run at 8 PSI 55 bar which does not meet your requirements RO DRIP 13 24 17 has a DU over 85 and 13 12 24XL has a DU over 90 both of which meet your requirements RO DRIP 13 12 24 XL will work well in this application You may be able to save cost by using the smaller diameter 13 24 17 but it may be difficult to achieve sufficient lateral movement of the wetted pattern with a 24 in 61 cm emitter spacing in sandy loam soil Try a small test area first You can also realize initial cost savings by lowering your uniformity target to 80 which allows you to use 13 12 24 also with a 5 8 in ID However the initial savings may be offset by increased water usage to compensate for the lower uniformity The correct answer depends on the specifics of your growing operation Placement of laterals The placement of drip tape defines its depth and distance from the plants and the distance between laterals In all cases the drip tape must be oriented with the emitters facing up to resist plugging from sediment settling Proper placement is determined by several factors including Soil texture and structure
63. ation 5 years Drip Tape RO DRIP 13 12 15 XL 13 mil 12 in spacing 15 GPH per 100 ft 7 8 in diameter 330 mm 30 cm spacing 186 LPH per 100 m 22 mm diameter RO DRIP USERS GUIDE CROP PRODUCTION Field Flowers Outside field flowers are usually grown in single or double rows either on level ground or in beds The most commonly used tape is 8 mil wall thickness with 8 in emitter spacing Cut flowers are grown in greenhouses on multiple row beds Use three laterals for a typical 36 to 48 in 91 to 122 cm bed in a greenhouse For a single or double row of flowers or for outside bulbs use a single lateral with an 8 or 10 mil wall thickness and an 8 in emitter spacing EXAMPLE Field Flowers Central Coast California USA a 607 Operation Auxiliary Equipment Crop ss d signa n field flowers Primary filtration sand media filters Location Central Coast California USA Secondary filtration none Field size 50 acres 20 ha SUUDMES ne s cued Es 09 R N t ae eater layflat Plants per acre 175 000 450 000 per ha MUI ces estades ei aaa none SEASON LL LL LL LL LL RE year round f Planting method Management Operation vintners direct seeded and transplanted Irrigation frequency 1 3 times per week Soil type clay to clay loam Irrigation duration 1 2 hours Maximum ET 30 in 75 mm per day Chemigation
64. avy gauge drip tape across pots or containers and secure it tightly at each end In some installations it is advantageous to string a wire over the containers and fasten the drip tape to the wire rather than laying it directly on the containers Install the drip tape with the outlets facing out to one side not straight down Alternatively pots or containers can be placed on a capillary mat that is irrigated with drip tape The water moves laterally across the mat and is drawn up into the container as it is used by the plant In the following example the grower successfully uses RO DRIP drip tape to irrigate potted flowers in a greenhouse EXAMPLE Potted Flowers mums Sacramento Valley California USA sa Pe RX Aa le gt PROF li lt J hi L K A Ni X lt eS A PE ANS A we i 5 lt ha 4 I LZ a 4 PARC 7 NS lt lt L Y aL gt Q i E 3 V A e aw lt DA Lp 1 A 4 o ae ZF ar GA 2 gt 2 P 160 qi 4 17 gt A A Operation Auxiliary Equipment Crop 24 sanis cod 4 sant mums greenhouse Primary filtration screen Location Sacramento Valley California USA Secondary filtration none DIZE 3 444443353 ee ated lt 3 5 acres 1 4 ha Submains vcs 4444906444399494 PVC Plants per acre 35 000 86 000 per ha Mull reiia a yana eee none DOASON er IAEE ERT non seasonal f Planting method transplanted Management Operation Soil type
65. c Layer and Drip Tape Installer tasks simultaneously In fact it is possible and now fairly common to shape beds install drip tape laterals install plastic mulch and even side dress beds with fertiliz er all ina single pass fig 4 5 These opera tions are often performed on several rows at once Packaged systems that install drip tape while performing other operations are avail able from a number of vendors Tape installation procedure subsurface For shallow subsurface systems mainlines and submains can be above ground vinyl layflat poly hose or buried PVC Deep sub surface systems should use PVC for mainlines and submains If using PVC submains above ground protect them from sunlight with a light covering of dirt Do not use steel or alu minum pipe Use the following steps to install drip laterals 1 Mount the spool on the shaft that feeds the injection shank 2 Setup and align the shanking tool so that when installed the drip tape emitters face upward RO DRIP USERS GUIDE RD4 2 The Roberts Difference RO DRIP spools utilize an industry standard bore for a 1 in shaft making it an easy fit for all commercially available injection equip ment 4 3 INSTALLATION AND STARTUP 3 Secure the beginning of the lateral s with a weighted object or a stake 4 Start and stop the tractor smoothly to prevent stretching or jerking of the drip tape through the installation tube Do not apply exce
66. ce Report Center for Irrigation Technology Fresno CA Hanson Blaine 1994 Drip Irrigation for Row Crops University of California Davis Davis CA ROBERTS IRRIGATION PRODUCTS INC 700 Rancheros Drive San Marcos CA 92069 3007 U S A 760 744 4511 800 685 5557 Fax 760 744 0914 www robertsirrigation com 2001 Roberts Irrigation Products Inc All rights reserved
67. d End of row extraction End of row extraction is the most common method of retrieval due to several advantages including End of row extraction is not limited by the speed of a tractor so it can be done faster When multiple retrieval heads are used if one head needs to be stopped for any reason the others can contin ue operating Pulling the tape along the row provides cleaning and water removal action which results in less damage and better spooling After disconnecting the laterals from the manifolds remove water by blowing them out with compressed air Pull the tape out using one or more retrieval heads mounted on a trailer at the end of the field fig 6 3 If laterals are buried they need to be manually removed from the ground before retrieval This is usually simple if the burial depth is less than 3 in In some cases it helps to soften the soil around the laterals by irrigating for a period of time before removal If the drip tape will be re used avoid stretching it or scraping it on rough soil or field stubble It sometimes helps to lift the drip tape off the ground and place it on top of the plants before retrieving it Several retrieval heads can be mounted on a single fixture to retrieve from several rows simultaneously NOTE The most common problem encountered during drip tape retrieval is damage from stretching Ensure tape is free of entanglements and water has been removed In hot climates if possible
68. d the middle of the bed should be left open for salt accumulation Laterals should not be placed so that the edge of the wetting pattern is under the center of a row surface shallow subsurface deep subsurface V ditch Figure 3 4 Lateral Depth Placement Uneven terrain Drip tape in hillside applications should be placed on the uphill side of the plant row to ensure a balanced wetted area in the root zone On steep slopes the laterals should be placed parallel to the contour lines of the terrain to minimize pressure differences caused by uphill or downhill runs RO DRIP USERS GUIDE 3 7 3 8 DESIGN Table 3 2 Typical Applications for Drip Tape Placement Depths Placement Application Single season e Retrieval and re use Applications where installation equipment is unavailable or the Surface field is small above ground Same as surface place ment V Ditch 2 3 in deep 5 8 cm deep Single or multi season Shallow sub surface 1 4 in 2 10 cm Multiple year Deep sub surface deeper than 5 in 13 cm RO DRIP USERS GUIDE Easy low cost installation Easy to confirm uniformity and operation Easy to locate and repair damage Easy to retrieve Easy low cost installation Easy to confirm uniformity Easy to locate and repair damage Reduced runoff Prevents tape wandering from heat or wind Reduced evaporation Reduced damage from cultu
69. d preparation or after transplanting and prior to putting plastic mulch over the beds Rain water can be helpful in decreasing salinity around plants during early growth but only if the holes in the plastic near the plant are large enough to permit infiltration of the rain water EXAMPLE Strawberries Central Coast California USA lt g Operation Auxiliary Equipment CIOD renda 004402424 strawberries Primary filtration sand media Location Central Coast California USA Secondary filtration screen Field size 40 acres 16 ha SUDMAING css sc a dies a a diada layflat Plants per acre 150 000 370 650 per ha MUIGH vra gatets e plastic mulch SEASON s Z tense ak ence Sep Jul Aug Dec f Planting method transplant Management Operation Soil type eiiean cents sandy loam Irrigation frequency 1 3 times per week Maximum ET 0 30 in 7 5 mm per day Irrigation duration 2 4 hours Water Source Qu LL vvel Chemigation yes Groundcover NONE Tertigation yes Crops rotated with celery Line flushing 2 4 times per season Time to maturity 60 days Filter back flushing automatic Average yield 3 500 5 000 cartons acre Duration of tape installation 9 10 months Drip Tape RO DRIP 5 8 40 5 mi
70. da USA Secondary filtration none Fieldsize 150 acres 60 ha SUDMAING xv c 40204 ved kika yee kak layflat Plants per acre 1 440 3 550 per ha Mulch none Season mid Feb end of June f Planting method direct seeded Management 0peration Soil TYPE ev qai agents distpeser acs sandy Irrigation frequency daily Maximum ET 0 35 in 9 mm per day Irrigation duration 1 4 hours Water Source well Chemigation nohe Groundcover rye in off season Fertigation yes Crops rotated with rye peanuts Line flushing none Timeto maturity 100 days Filter back flushing based on well Average yield 25 tons acre 56 tons ha Duration of tape installation 1 year Drip Tape RO DRIP 8 12 24 8 mil 12 in spacing 24 GPH per 100 ft 5 8 in diameter 200 mm 30 cm spacing 298 LPH per 100 m 16 mm diameter RO DRIP USERS GUIDE CROP PRODUCTION Lettuce Iceberg and mixed lettuce are typically direct seeded on double row 40 to 42 in 102 to 107 cm beds Rows are spaced 8 to 12 in 20 to 30 cm apart with a single drip lateral in between the plant rows placed on or near the surface Seed is normally planted at 2 to 3 in 5 to 8 cm spacing using pelleted seed and precision pla
71. daily irrigation is good practice to ensure your plants are not stressed Irrigating several times daily may result in reduced distribution uniformity since the repeated filling and draining of submains and laterals with each irrigation results in heavier irrigation at the low points of the field As described above however pulse irrigating can help with the development of a good wetting pattern making it a good choice in some cases NOTE Drip irrigation only wets soil near the plants Roots only develop in the wetted area and as a result can be more localized than with other irrigation methods This normally does not cause problems but it makes irrigation frequency critical Because the water holding capacity in the root zone is smaller an extended period of time without irrigating can easily cause plant stress During hot weather conditions daily irrigation may be necessary to avoid crop damage from water stress How long to irrigate irrigation duration Once you have determined an irrigation frequency you must determine the duration of each RO DRIP USERS GUIDE RD5 1 The Roberts Difference Roberts Irrigation manufac tures several high flow rate products with close emitter spacings that are specially designed to form good wetted patterns in soils with high sand content These include 8 in 40 GPH RO DRIP 20 cm 497 LPH and 4 in 60 GPH RO DRIP 10 cm 745 LPH RD5 2 The Roberts Difference Roberts Ir
72. deeper than 8 in emitter spacings are greater than 12 in or the soil has a high sand content water may not make it to the surface where it can be used by the seeds In these cases sprinklers must be used for germination Even under ideal water movement conditions some growers prefer sprinklers because of their physical impact that drives air out of the soil and results in favorable germinating conditions for some crops FERTIGATION One of the principal advantages of drip irrigation is the direct access it provides to the root zone for injection of fertilizer and other chemicals This allows frequent accurate and economical application of nutrients to field crops even those grown with mulch throughout the growing season With proper monitoring and testing drip irrigation allows you to quickly adjust nutrient levels with precision that is not possible with furrow or sprinkler irrigation Liquid Fertilizers Fertilizers are widely available in liquid form that can be directly injected into your drip RO DRIP USERS GUIDE 5 13 5 14 MANAGEMENT irrigation system Many fertilizer dealers provide liquid fertilizer blends specifically for drip fertigation which may include N P K and minor nutrients These blends can be region and or crop specific While some fertilizer blends can be expensive drip fertigation maximizes their ben efits by applying them precisely and efficiently Most clear liquid fertilizers can be injected di
73. e Salinity management e Crop grown ET requirements RO DRIP USERS GUIDE 3 5 3 6 DESIGN General cultural practice Seeding vs transplanting Use of plastic mulch Crop rotation Equipment availability Field topography Each field situation has many variables and the best solutions come from experience Experiment with small trial plots to find the best lateral placement and application rates to meet the needs of your crop Refer to the crop examples in appendix B to see how experienced drip tape users have made lateral placement decisions Following are a few general guidelines Position of laterals The placement of drip tape relative to each plant row depends on the amount of lateral movement of water allowed by your soil type and the requirements of your plants In general lateral movement of water in light high sand content soils is difficult to achieve so drip tape should be placed close to the plant row usually 2 12 in 5 30 cm Conversely larger distances up to 24 in 61 cm are acceptable for high clay content soils which promote easy lateral water movement and which may result in ponding due to low infiltration rates Drip tape should also be placed close to the plant row if plants are direct seeded This provides the high soil moisture required by the seeds as well as additional salt leaching which may be necessary during the early salt sensitive growth stages When direct seeding in sandy s
74. e appeal of using the latest technology Drip irrigation is capable of delivering on each of these promises However you should carefully consider your unique goals and situation when deciding whether drip irrigation will work for you A drip irrigation system requires a significant investment in time and money The first step in this investment begins here by taking time to become fully informed before initiating your drip irrigation project Your goals for this initial investment in time should be to Develop awareness about what it takes to design install and operate a system Determine your ability financial and otherwise to proceed Assess the level of commitment you are willing to make to develop a properly designed and managed drip irrigation system Locate a qualified irrigation dealer with drip experience You are the most important component in the success of your drip irrigation system CULTIVATING A LONG TERM VIEW Growers are naturally inclined to take a long term view on things This common sense wisdom is especially valuable when applied to the planning of a drip irrigation system Your initial investment in terms of equipment and know how may take 2 or more years to recover However your investment should be seen not only in terms of crop quality and yield but as an intelligent response to global trends in diminishing natural resources reduced government subsidies and increased environmental regulation ACCES
75. e known dielec tric constant for water to report percentage moisture content Measures the dielectric con stant of the soil solution by measuring the change in fre quency of an RF pulse Uses this measurement along with the known dielectric constant for water to report percent age moisture content Uses measurements of the permeation of soil by a radioactive source to determine hydrogen content which is proportional to mois ture content No instrumentation cost Observation of soil and plants may reveal prob lems that could be missed with automatic sensors Low cost Reliable for tension below 80 cb Not affected by salinity Very low cost Can easily be read remotely High accuracy Fast measurement time Can easily be read remotely Low maintenance requirement High accuracy Readings not affected by salinity Can easily be read remotely Low maintenance requirement High accuracy Non destructive Tests a relatively large volume of soil Cannot be automated Will yield inconsistent results if several people are taking mea surements Not accurate in dry soil above 80 cb Relatively high mainte nance requirement Poor accuracy in wetter soil below 1 0 bar Readings can be affect ed by salinity e High maintenance requirement Relatively high cost Readings can be affect ed by salinity Calibration required Relatively high cost
76. e of the problems that can be diagnosed by keeping track of system flow rates Any of these problems should be addressed immediately to RO DRIP USERS GUIDE 555 5 6 MANAGEMENT avoid serious crop damage Note Tables 5 5 and 5 6 are intended to present examples of problems that can be diagnosed through regular monitoring They are not a comprehensive list of problems that can occur with your specific drip irrigation system Most flow meters provide instantaneous readings of flow rate as well as a reading of total flow The totalized reading is more accurate than the instantaneous reading and can be used to calculate the average flow rate or application rate over a given time This reading can also be used to indicate the total water usage during an entire season Table 5 5 Problems Diagnosed from System Flow Rates Emitter plugging Gradual decrease in flow rate Could indicate pump wear or filter clogging check pressures Stuck or plugged control valve Sudden decrease in flow rate Other flow restriction check pressures Water supply failure check pressures Gaal race Na flow rats Incremental damage to laterals from insects or other pests Damaged or broken lateral Damaged or broken submain Damaged or broken mainline Pressure regulator failure Sudden increase in flow rate Table 5 6 Problems Diagnosed from System Pressures Debris buildup in filters e Inadequate flushing of filters Large pressure
77. e to one or more submain risers which supply the individual submains in the system They are most commonly made from buried PVC although poly hose or layflat can be used in small or portable installations Do not use metal pipe espe cially aluminum because it can react with chemicals that are injected through the system and plug emitters Important considerations in the design of mainlines include the following e Mainlines should be carefully laid out to minimize both material cost and pumping cost Tradeoffs between initial material cost and ongoing pumping cost must be made when sizing mainlines e Thrust blocks should be installed on large mainlines at points where flow changes direction e Mainline sizes should be specified such that flow velocities do not exceed 5 ft sec 1 5 m sec Up to 8 ft sec 2 4 m sec is acceptable in some cases where water is free of sand and care is taken to open and close valves slowly Pressure relief valves should be installed at low points and at the end of mainlines e Air vacuum relief valves should be installed at high points and downstream of any valves e Flush valves should be included at the end of mainlines Consult a qualified irrigation designer to design mainlines that meet these requirements as Figure 3 7 Connection of a Submain to a Mainline cost effectively as possible Connection of Mainlines to Submains A pressure regulator at the start of each submain can improve distribution
78. ead to problems with soil permeability RO DRIP USERS GUIDE 5 17 5 18 MANAGEMENT Observe the following cautions when injecting gypsum into a drip irrigation system e Only inject high purity gypsum e Only inject finely ground gypsum 98 should pass through a 200 mesh screen e Always locate the injector before filtration equipment Do not inject at excessively high rates that exceed the solubility limit of gypsum in water Table 5 10 Permeability Problems Caused by Poor Water Quality Water Quality Problem High SARa resulting from high Na Ca ratio High SARa resulting from high bicarbonate HCO3 content Pure irrigation water RO DRIP USERS GUIDE Description As proportion of sodium attached to clay particles increases soil tends to run together resulting in reduced water penetration rates In extreme cases alkali soil soil can no longer be used for growing HCO3 removes calcium from the soil by binding with it to form CaCO3 calcium carbonate The calcium removed from the soil complex is replaced with sodi um and the soil becomes sodium rich Interaction between the salinity of water and various ions has an effect on permeability Appendix B shows that high SARa can cause more of a prob lem if EC is low Very pure EC lt 0 2 dS m water can cause severe prob lems even if there is a high proportion of calcium in the irrigation water Possible Solutions Increase calc
79. efore designing your system and especially before adding any chemicals or fertilizer to your water RO DRIP drip tape is technical specifications to thickness which means tion and retrieval Salinit Table 2 1 Soil Solution Salinity Level water sources and many Re Cause E gueren fertilizers carry some level of dis Salinity EC of solved salt that accumulates in the Crop Soil Exctract soil during regular irrigation In arid wai regions where salinity is a significant Strawberry problem this buildup can affect the health of your plants In such cases your system design and operation must account for and properly manage salt buildup Your water quality Cabbage Cucumber Muskmelon Potato i analysis should include a report of the salt content and type See appendix A for tables to assist you in interpreting Bean Lettuce Pepper Raddish Onion Carrot Corn Artichoke Sweet Potato gives the salt tolerance of several Tomato Broccoli popular crops in terms of the salinity of the soil solution Cotton after germination RO DRIP USERS GUIDE 2 3 PLANNING NOTE In areas with low rainfall salinity of the soil solution is typically higher than the salinity of your irrigation water Even with good irrigation management soil solution salinity can be 1 5 to 3 times the irrigation water salinity The initial effects of salt buildup can be subtle It is important to understand t
80. ength 1000 ft 305 m Slope 0 5 Soil Sandy loam Using the charts in appendix D RO DRIP 13 12 24 has a DU of slightly more than 80 for a RO DRIP USERS GUIDE DESIGN Table 3 1 Drip Tape Design Parameters and their Effect on Performance Parameter Wall thickness Emitter spacing Nominal flow rate Diameter Effect on Performance thicker walls improve resistance to damage from pests and or installation thicker walls allow higher operating and flushing pressures thicker walls make longer term instal lation possible closer emitter spacings result in high er flow rates closer emitter spacings are sometimes required for seed germination closer emitter spacings can provide a better wetting pattern in some light soils larger emitter spacings can deliver low flow rates without increasing the risk of plugging higher flow rates result in more lateral movement of water in sandy soils higher flow rates reduce the risk of emitter plugging lower flow rates allow longer lateral runs lower flow rates allow improved infiltration of water in heavy soils large diameters allow longer lateral runs Thicker drip tape is more costly and is usually used where the field is rough for sub surface placement and for long term placement Thick tape is also used for better pest resistance Thinner tape is used for single season crops Choice of spacing is based on planting method germin
81. ensor If you are using a low cost sensor such as a tensiometer or gypsum block you can install several Table 5 7 Important Soil Moisture Levels Saturation 0 3 cb 15 60 depending on soil type Field Capacity 10 25 cb depending on soil type 10 50 depending on soil type Permanent Wilting 15 bar approx 2 30 depending on soil type sensors in the field each at a different depth and location Take readings in sets of three measurements just below the surface in the middle of the root zone and below the root zone in the row between plants table 5 8 Use two or more sets within an irrigation block to verify that measurement sites are representative Additional sites may be helpful in non uniform soil Soil moisture sensors A variety of sensors are commercially available for measuring soil moisture Each sensor either measures moisture content or tension directly Table 5 9 summarizes several types of moisture sensors Numerous other types are available fig 5 1 RO DRIP USERS GUIDE 5 7 5 8 MANAGEMENT Table 5 8 Sensor Depth Reflects soil moisture conditions in the root zone during early plant growth or 6 in 15 cm throughout the season for shallow rooted crops Monitors the root zone as plants mature and their roots enlarge Use this depth to monitor 12 in 30 cm irrigation during most of the plant s life j Monitors the degree of leaching below the root zone should not change during 18 or 24 in
82. er can occur Care should also be take with muriatic acid which is high in salt NOTE When adding acids for extended periods of time as part of irrigation inject them downstream of filters to avoid corrosion of metal filter components Always perform a jar test before injecting chemicals into your system to ensure they do not precipitate when added to your irrigation water This is particularly important with acids that are injected downstream of any filtration NOTE Some filters such as stainless steel media filters are specifically designed to resist corrosion from acids These filters are ideal because they allow acids to be injected upstream Consult your filter supplier NOTE Some filter media materials can buffer back acids and reduce their effectiveness NOTE Inject acid into the center of the mainline flow or into a mixing chamber to prevent it from damaging pipe walls before it becomes diluted in the irrigation water CAUTION Never inject acid into aluminum pipe Injecting acids in high concentrations can sometimes correct problems that have occurred due to poor quality irrigation water or mismanagement of a drip system See Clearing Clogs if they Occur below NOTE Acid is heavier than water When high concentrations are added it can lay down and remain in your drip system after injection is complete If high pH fertilizers are later added precipitation can occur Flushing laterals Even when a properly desig
83. er plugging through proper system design and maintenance In the event that plugging does occur however it is sometimes possible to dislodge or dissolve clogs by adding chemicals Injecting acids in higher concentrations can sometimes correct plugging problems caused by RO DRIP USERS GUIDE 5 11 RD5 4 The Roberts Difference The emitters of RO DRIP drip tape incorporate a unique expandable flow channel fig 5 3 which provides a second line of defense against plugging during high contaminant conditions If plugging occurs increase the supply pressure to the maximum recommended pressure see RO DRIP PERFOR MANCE SPECIFICATIONS for maximum pressure val ues for several minutes In most cases the channel will expand open to purge obstructions and restore flow 5 12 MANAGEMENT Figure 5 2 Open Laterals and a Flushing Manifold in Action algae and bacterial growth or mineral deposits High acid concentrations can also kill roots that have grown into lateral outlets root intrusion Note acid is very dangerous and extreme care must be taken Always add acid to water Never add water to acid When possible have your chemical company mix acids for you Note Many states require permits for the use and storage of concentrated acids usually over 52 con centration Storage labeling and safety equipment requirements are often specified by law Use the following procedure to correc
84. es hectares 0 4047 sq meters sq centimeters 10 000 sq feet sq inches 144 sq meters sq feet 10 764 sq feet sq yards 0 111 sq centimeters sq inches 0 1549 sq feet sq meters 0 0929 sq inches sq centimeters 6 452 RO DRIP USERS GUIDE ENGINEERING CONVERSION FACTORS APPENDIX F ENGINEERING CONVERSION FACTORS VOLUME To Convert To Multiply by To Convert To Multiply by Acre Feet Gallons 325851 Cubic Meters Liters 1000 Acre Inches Cubic Feet 3630 Cubic Meters Gallons 264 2 Cubic Yards Cubic Meters Cubic Meters Cubic Feet Cubic Yards Liters Cubic Meters Cubic Yards Cubic Yards Cubic Feet Liters cubic Meters Cubic Yards Cubic Inches Liters Cubic Yards Cubic Yards Gallons Liters Cubic Feet Cubic Fee Gallons Liters Gallons Cubic Fee Cubic Inches Liters Cups Cubic Fee Cubic Yards Liters Quarts Cubic Fee Cubic Centimeters Liters Pints Cubic Fee Cubic Meters Liters Cubic Inches Cubic Fee Liters 28 32 Liters Cubic Centimeters 1000 Cubic Fee Acre Inches 0 000275 Cubic Centime Cubic Feet 353x102 Cubic Fee Acre Feet 0 0000230 Cubic Centime Gallons 0 000264 Gallons Acre Feet 0 00000307 Cubic Centime Pints 0 00211 Gallons Cubic Feet 0 134 Cubic Centime Cubic Millimeters 1000 Gallons Cubic Inches 231 Cubic Centime Cubic Inches 0 061 Gallons Cubic Yards 0 005 Cubic Centime Liters 0 001 Gallons Cubic Centimeters 3785 Cubic Centimel Quarts 0 0011 Gallons Cubic Meters 0 003
85. es in this section are general recommendations and are not intended to suggest complete design or production practices Please consult your local Roberts Irrigation Products dealer for specific design applications DESIGN GOALS Before designing your drip irrigation system use the information collected in the PLAN NING section to establish clear design goals Because of the conflicting requirements of a drip irrigation system some of the following goals may need to be adjusted after you begin the design process e Uniformity Define the minimum uniformity your design will need to achieve keeping in mind that higher uniformity designs may result in higher cost See Irrigation Efficiency in this section e Application Rate Know what the application rate requirements will be to replace peak ET System Life Decide whether your drip tape laterals mill be used for a single season or for several years Also determine how long the other system components should last System Cost Know your sensitivity to cost which may influence your decisions about target uniformity and system life Your challenge will be to design a system that meets these conflicting goals You will need to RD3 1 make tradeoffs between uniformity system life and system cost System cost encompasses both one time installation costs and ongoing operating costs which also may conflict The Roberts Difference RO DRIP employs an COMPONENTS While there are many differe
86. estrictions properly Submains are carefully sized so that pressure lost due to friction offsets pressure gained due to elevation change This results in larger diameter pipe at the top of the slope telescoping down to smaller diameters further down the slope Telescoping submains can also be used on flat ground to reduce cost of pipe Telescoping submains If small diameter transfer tubes are used to connect laterals to submains their lengths can be set to vary the amount of flow restriction they provide Short tubes are installed at the top of the slope and long tubes are installed at the bottom Charts and formulas are available that give the friction loss caused by a given length of transfer tube or trial and error can be used Variable length transfer tubes 314 RO DRIP USERS GUIDE DESIGN slope is severe Every 5 feet 1 5 m of elevation change will cause approximately 2 psi 0 14 bar pressure change which is enough to affect uniformity There are several ways to minimize the effects of slope on uniformity The submain should run downhill with the water supply at or near the top Refer to table 3 9 for methods to minimize the effect of submain pressure variations Air vacuum telief at the high points of sloping submains is critical to prevent vacuum conditions that can suck dirt particles into the emitters and cause plugging when the system is drained Design of Mainlines Mainlines distribute water from the sourc
87. g problem can result in complete failure of your drip irrigation system Such a failure can occur mid season when it is not possible to make repairs or replacements Include the following steps in your maintenance program to prevent this from happening Filter maintenance The importance of proper filtration was discussed in the DESIGN section Once your filters RO DRIP USERS GUIDE Method or Device Advantages Disadvantages BY FEEL moisture content TENSIOM ETER Tension GYPSUM BLOCR Tension TDR SENSOR moisture content FDR SENSOR moisture content NEUTRON PROBE moisture content MANAGEMENT Table 5 9 Moisture Sensors With experience it is possible to learn with a fair degree of accuracy how your soil looks and feels when it is at field capacity Look and feel includes observation of the soil as well as the crops for signs of stress Soil capillary action removes water from a cup through a porous material creating a vacuum that is equal to the tension of the soil matrix A vacuum gauge gives tension readings in bar or centibar Soil water permeates a porous block of gypsum with two embedded electrodes that measure resistance resistance meter is calibrated to give readings of tension in bar or centibar Measures the dielectric con stant of the soil solution by measuring the time required for an electrical pulse to travel through a spike or probe Uses this measurement along with th
88. h clear plastic mulch Water droplets on the surface of the plastic act as magnifying lenses which can cations This includes a focus sunlight to burn and damage drip tape Pare pa Greenhouse Nursery Installations Drip tape is an effective method of irrigating nursery and greenhouse plants It is commonly used to irrigate both potted plants and field plants The increased level of control made possible with drip tape results in higher quality crops with reduced incidence of disease closely spaced plants Potted plants To irrigate potted plants drip tape is laid across pots or containers and secured tightly at each end fig 4 8 In some installations it helps to string a wire over the containers and fasten the drip tape to the wire rather than Figure 4 7 Simultaneous Installation of Drip Tape and laying it directly on the containers Emitters Reeve MUIA should face to one side instead of facing up to prevent water from running along the tape and missing the pots Field nurseries In field nursery applications drip tape is either laid on the surface or buried 2 3 in 5 8 cm below the surface see figure 4 9 4 4 RO DRIP USERS GUIDE INSTALLATION AND STARTUP CONNECTING LATERALS TO SUBMAINS Drip tape laterals can be connected to submains using fittings and or transfer tubes Connect laterals to the submains as part of an integrated startup procedure that includes flushing mains and submains See Startup
89. han 1 The discharge exponent of a drip emitter can be calculated by measuring its discharge rate at two different pressures The equation which relates pressure to discharge rate for a drip emitter is q KP RO DRIP USERS GUIDE COEFFICIENT OF VARIATION AND EMITTER DISCHARGE EXPONENT where P is the pressure applied to the emitter q is the discharge rate x is the discharge exponent and K is a constant By measuring discharge rates at two different pressures you can calculate the exponent as follows q KP q KP q P _ log q q log P P where q is the discharge rate measured at pressure P and q is the discharge rate measured at pressure P Most drip tape manufacturers publish the discharge exponent of their products Several independent labs also test discharge exponents and compare them among manufacturers This user guide tells you how to design your drip system to have minimal pressure variations from elevation changes and friction losses Even a well designed system however can have higher pressures in some parts of the field than in others If you select a drip tape product with a low x value you can avoid the problems of higher discharge rates in some parts of the field than in others and low distribution uniformity RO DRIP USERS GUIDE C 3 SAMPLE RO DRIP PERFORMANCE CHARTS Following are sample performance charts for three RO DRIP products XX 12 24 12 inch emitter spacing
90. hat salt damage to your crop may not be apparent until it is too late to prevent Fortunately proper drip irrigation practices include ways to manage salinity and to keep it out of the root zone See MANAGEMENT Managing Soil Salinity for guidance on monitoring and managing salt buildup in the soil WATER REQUIREMENTS Your system must be designed to supply enough water to exceed your crop s water requirements during the hottest day of the season while also providing enough water for line flushing and salt leaching where needed Water requirements are influenced by the following factors Plant size Leaf canopy e Soil type Water quality Solar radiation e Growth stage Ground cover Rainfall Ambient temperature and humidity e Wind conditions The Roberts Difference System efficiency Fertilizers and chemicals used The highly plug resistant e System operations e g leaching flushing filter backwashing design of RO DRIP makes it The interaction of these factors can be complex However by making a few measurements and by referring to standard formulas and tables it is relatively easy to calculate your actual quality is a concern irrigation requirements and develop a proper irrigation schedule Most crops reach their full potential if the soil in the root zone is at all times maintained at a moisture content that is near the soil s maximum water holding capacity The goal of a drip irrigation system throughout m
91. ht covering of dirt Do not use steel or aluminum pipe Use the following steps to install drip laterals 1 Mount the spool on a low stand at the front end of the row 2 Pull the lateral along the row taking care not to drag it on the soil surface fig 4 1 Lay the drip tape with the emitters facing up Note If the ground is rocky or there is stub ble in the field install the drip tape by carrying the spool down the row This avoids damage caused by dragging the drip tape fig 4 2 3 Place a shovel full of dirt on the drip tape every 10 to 15 ft 3 to 4 5 m to prevent twisting or wandering fig 4 3 Avoid stretching or jerk ing the lateral during installation 4 Leave extra length at both ends of each later al to allow for expansion and contraction and to connect to the manifolds Mechanical Tape Installation Installation equipment an overview Figure 4 2 Walking Spools Along a Row The basic component used in all mecha RO DRIP USERS GUIDE INSTALLATION AND STARTUP Figure 4 3 Placing Dirt on a Lateral chased from a number of suppliers nized installation is the injection shank Its purpose is to accurately locate the drip tape to the point of installation either on or below the surface and in subsurface installations to dig a trench for the lateral One or more spools and injection shanks can be mounted together on a tool bar Figure 4 4 shows a Tube Type injection shank which is popular
92. ia sers RA A9 4 A2 ances 4 none SEASON v ia tans desa emeten te di Apr Oct f Planting method transplant Management Operation Soil type sandy to sandy loam Irrigation frequency daily Maximum ET 0 35 in 9 mm per day Irrigation duration 4 6 hours Water Source well Chemigation yes Ground cover fallow with grain Fertigation yes Crops rotated with 2 3 yrs melons grain Line flushing yaa s puranira taqsa minimal Time to maturity 90 150 days Filter back flushing minimal Ave yield 11 25 tons acre 25 56 tons ha Duration of tape installation 1 year Drip Tape RO DRIP 5 12 24 5 mil 12 in spacing 24 GPH per 100 ft 5 8 in diameter 127 mm 30 cm spacing 298 LPH per 100 m 16 mm diameter B10 JRO DRIP USERS GUIDE CROP PRODUCTION Cotton Cotton is a deep rooted crop 48 in 122 cm or more with a 6 to 8 month growing season Cotton is typically planted in beds spaced 30 to 40 in 75 to 102 cm apart Seeds are typically planted 3 to 4 in 8 to 10 cm apart in single rows A carefully managed drip irrigation system will allow you to grow cotton using saline water However the seeds should be germinated and the stand established using water of at least average quality up to 800 ppm total dissolved salts After the stand is established
93. il type has a major influence on the emitter spacing tape placement depth and flow rates of a good system design DRAINAGE Inadequate drainage leads to inadequate aeration of soil increased incidence of disease limited root zone size and limited ability to leach salts away from the root zone Drainage problems can be caused by perched water tables compaction layers and stratified soils Adding gypsum or organic amendments to heavy soils can improve drainage although amendments that contain salt should be avoided when possible Where drainage is poor deep 30 in 76 cm subsoiling and chiseling every 1 to 4 years may be necessary In some cases deep plowing can maintain good drainage for longer periods of time If a high water table inhibits drainage drainage channels or subsurface drain systems may be required WATER AVAILABILITY Water availability and quality are central factors in the design of your drip system Unlike traditional sprinkler and furrow irrigation drip irrigation places very specific demands on the quality and availability of your water source It is important to design your system so that optimum soil moisture is maintained throughout the growing season The system must be capable of supplying your crop s peak needs plus any additional amounts needed for flushing Although drip irrigation may use less water than required by other irrigation methods it requires it on a consistent and reliable basis Typical drip syste
94. ineral deposits can build up inside of laterals and eventually plug emitters even if a very high level of filtration is used The rate at which this occurs depends on your water source and climate In many cases buildup of organic matter and minerals can be reduced or eliminated with regular injection of chlorine or acids or both Chlorine Injection The best defense against buildup of algae and many types of bacteria is chlorine Chlorine is available in three forms sodium hypochlorite liquid chlorine commonly used for household bleach calcium hypochlorite dry chlorine used for swimming pools and gas chlorine Sodium hypochlorite and calcium hypochlorite are high in salts and must be used carefully with salt sen sitive plants or in soils that are already high in salt Gas chlorine is an extremely hazardous sub stance and must be contained and used with great care Use chlorine as follows To control algae iron bacteria and sulfur add chlorine until a concentration of 2 10 ppm free chlorine is achieved at the end of the furthest lateral from the injection point Maintain this level for 30 60 minutes This can be done once every two to three weeks or as frequently as after each irrigation cycle depending on the chlorine concentration used and level of organic material in the irrigation water e Alternatively chlorine can be applied continuously to obtain concentrations of 0 5 to 1 ppm at the ends of the furthest lateral Use highe
95. ip irrigation systems occurs during tape installation If you use mechanical tape laying equipment it should be carefully designed and free of burrs sharp edges mud sticks and stones Whatever method you use to install your system following a few well tested procedures can help you avoid expensive and time consuming The Roberts Difference repairs a eee i RO DRIP s unsurpassed Accurate placement of laterals can result in increased water distribution uniformity and better P movement of water through the soil allowing you to take advantage of the full potential of your uniformity simple system This section explains how to install drip laterals how to connect them to submains and installation and retrieval how to properly start up and check your system for trouble free operation over the long run reduced infrastructure and lower cultivation costs KEN CONG ERIS a A I make it the performance Precise installation of your system can result in more uniform performance and easier retrieval I A s leader for any length of e Always install drip tape with the outlets facing up to prevent plugging by sediment that may settle during operation e The installation shank is the main tool used for mechanized drip tape installation manne de All equipment that makes contact with the drip tape during installation must be free of burrs and other sharp edges Before irrigating test the entire system to confirm prope
96. irrigation divided by RO DRIP USERS GUIDE MANAGEMENT the application rate Amount to be applied 42 in 42 T UC 545hr AR 077 inper hr 077 or approximately 51 2 hours Adjusting your irrigation schedule Confirming the amount of water applied It is important to verify your irrigation schedule by taking direct readings from flow meters Confirm that the system is applying the amount of water each day that you intended it to in your schedule as described in Monitoring below Make adjustments as necessary Adjusting your schedule Since ET can vary from day to day and even from field to field within the same geographic area it is always necessary to adjust your schedule based on observations of the wetted pattern and measurements of soil moisture The section below Monitoring Soil Moisture describes how to use moisture sensing devices to measure the amount of water in your soil If soil moisture measurements in the middle of the root zone indicate the water level is consistently below field capacity or the soil is consistently saturated adjust your irrigation schedule by changing the irrigation duration as shown in table 54 Try making small modifications over several cycles before making any drastic revisions to the schedule Table 5 4 Adjusting Your Schedule with Soil Moisture Response Consistent high moisture low tension Too much water applied Decrease duration readings indicating field is saturated
97. ium Reducing the pH of the irrigation water through acidification or by using RO DRIP USERS GUIDE MANAGEMENT phosphoric acid can usually control precipitation White phosphoric acid can be safely injected into most irrigation water as long as the pH of the solution is low Potassium K Soluble potassium is a positively charged ion that easily binds to negatively charged clay particles As a result when it is applied from the surface it usually only penetrates the top few inches where it can not always be used by the plants Subsurface drip irrigation can help solve this problem by delivering potassium directly to the active part of the root zone In some cases foliar sprays of potassium are more effective All potassium fertilizers are water soluble and precipitation problems are infrequent Minor Nutrients Minor nutrient availability to plants is highly pH dependent Metal micro nutrients Cu Fe Mn Zn become less soluble in high pH soils while S Mo B C and M become less soluble in low pH soils Chelated micro nutrient metals are a convenient way of making metal ions available to the plant root zone Chelates are expensive but they can be very effective both at delivering injected metal micro nutrients to the plant root zone and at making metal ions already resident in the soil available to plants The ability to utilize expensive fertilizers such as chelated metals as efficiently as possible is one of the many benefits
98. ium content of water by injecting gypsum if damage to soil is already done soil amendment with gypsum may be required Reduce HCO3 in water by injecting sul furic acid sulfur dioxide or other acid If damage to soil is already done soil amendment with sulfur or gypsum may be required Injecting or ammending with gypsum can improve permeability of pure water both by increasing EC and by increasing calcium content RETRIEVAL Your drip irrigation system or at least the laterals will ultimately be retrieved from your field This may be after several years in a subsurface system or after a single crop in a surface or shallow buried application In some cases the laterals may be retrieved and disposed of In other cases they may be re installed in your field after being stored for a period of time Still in other cases they may be moved to another location and re installed The best method of retrieval depends on the specifics of your growing operation The choice is affected by cultural practices drip lateral placement residual crop material soil moisture and economics This section helps you evaluate the important variables and decide whether to re use or dispose of your drip tape after removing it from the field The basic procedures and equip ment used for drip tape retrieval are also described for each method KEYT CONCERTS The best retrieval method for you depends on whether you will re use or dispose of the drip t
99. just during system operation e Confirm that the injector you specify is capable of low flow rates rates as low as 0 1 of the total irrigation flow may be required e Check with regulatory agencies for specific requirements regarding backflow prevention It may be necessary to use several injectors to achieve desired flow rates and to allow separate injection of incompatible chemicals Before adding anything to your pipelines test its compatibility with your water using a jar test which is a simple test of precipitation risk See MANAGE MENT Fertigation for instructions on performing a jar test There are many types of injectors to choose from fig 3 12 Table 3 13 summarizes the features of some common injection equipment Injection System Materials Highly concentrated acids and other corrosive chemicals are commonly injected into drip irrigation systems Be sure the components of your injection system including tubing and fittings are made from suitable materials While PVC and other commonly used materials are highly resistant to diluted acids concentrated acids can degrade them over time Injection should be into the center of the water flow in the mainline or in a mixing chamber so the chemical is diluted before it makes contact with the inside wall of the pipe Tubing and fittings made from Kynar PVDE plastic are resistant to concentrated acids and other chemicals used in irrigation systems Kynar is a registered trademark of
100. k and re enters the water flow downstream of the restriction A tank stored above the water flow drips the chemical into the water at a constant rate Water passing over a narrow Opening causes a vacuum which pulls the chemical into the water path Many types available all require power to push liquid forward Simple Does not allow control of injection rates the initial concentration is high er than the final concentration Causes a pressure drop in the main irrigation line Allows control of injection rates e Simple Requires a float valve and a metering valve Allows control of injection rates There is a 10 30 pressure drop caused by friction in the venturi eCan be used in conjunction with a small pump to reduce pressure loss Allows precise control of injection rates Water powered models are available INSTALLATION AND STARTUP Drip tape installation methods range from manual placement of single laterals without the use of tractors or other equipment to automated injection of several laterals simultaneously in combination with other operations such as bed shaping and mulch laying The right method for your operation depends on a variety of factors including the size of your field lateral placement depth and the equipment available to you Careful installation and startup of your system can reduce initial cost and enhance long term performance Experience has shown that most damage to dr
101. l 8 in spacing 40 GPH per 100 ft 5 8 in diameter 127 mm 20 cm spacing 497 LPH per 100 m 16 mm diameter RO DRIP USERS GUIDE B 3 CROP PRODUCTION Melons Melons are typically direct seeded 3 to 4 in 8 to 10 cm from the drip lateral in single rows at 12 in 80 cm in row spacing with 60 to 84 in 152 to 213 cm between rows Watermelons will generally have an in row spacing of 24 to 36 in 61 to 91 cm with 72 to 108 in 183 to 274 cm between rows Laterals are usually placed on or near the surface Two laterals placed 4 to 6 in 10 to 15 cm on either side of the seed line may be required in lighter soil if there is difficulty is achieving an adequate wetted area for deep rooted melon crops Heavy watering late in the season can lead to soft poor quality melons This is especially true in heavier soils Irrigation as a general rule should be reduced to about one half of ET evapo transpiration 2 weeks before harvesting is expected to begin Continue reduced irrigation imme diately after each harvest to support subsequent production The best time to begin reducing irrigation and the amount to cut back depends on soil type rooting depth total wetted area and the usable water reserve in the soil EXAMPLE Watermelons North Central Florida USA B 4 Operation Auxiliary Equipment CHOP otis hawt chee cate on ed watermelons Primary filtration screen Location North Central Flori
102. l short irrigation cycles with high application rates help promote lateral movement of water resulting in better wetting patterns for light soils Pulse irrigation where the system is operated several times a day for short durations can further widen the wetted pattern Long duration at a low application rate results in better infiltration of water in heavy high clay content soils The right irrigation cycle depends on the specifics of your field experiment to find out what works best Determining Your Irrigation Schedule How often to irrigate irrigation frequency The irrigation frequencies used in drip irrigation are typically quite different from those used in other methods of irrigation The increased control offered by drip systems allows you to apply small amounts of water daily or several times a week without significant loss to evaporation or surface runoff As a result irrigation can be scheduled to replace water as it is used by the plant ona daily basis This ability to use frequent irrigation to keep the soil moisture level near field capacity is a unique advantage of drip irrigation In most cases irrigation can take place several times a day once a day or several times a week Research has shown that there is little difference between these as long as enough water is applied each time although there are some exceptions During consecutive days of hot dry weather or when young seedlings are grown in coarse textured soil
103. lable from 20 600 mesh Available in 10 30 mesh Sized according to peak water requirement and particulate type RO DRI P Cleaned by backflush ing Available in carbon steel stainless steel and fiberglass A settling basin may be required if large amounts of silt or clay particles are present Several tanks can be used in parallel for large flow rates Clean by flushing Easily clogged by organ ic matter Self cleaning Low maintenance Does not remove organ ic matter Not 100 effective usually used as a pre filter Cleaned by water flow and additional spray nozzles Booster pump is usually necessary after this filter Cleaned by backflush ing Can handle high flow conditions by installing several banks of disk filters e Not for use with large amounts of sand Cleaned by rotating water jets Cleaned by draining and removing buildup Care must be taken to control algae growth Inlet must be away from outlet USERS GUIDE 3 17 3 18 DESIGN Your choice among pump types and sizes should be determined by the optimum operating pressure and flow rate of your system Once you have determined the requirements of your system you can choose the most efficient combination of pump and power source by consulting catalogs of pump performance curves Pump specification is an in depth topic that is not covered in detail here Many pump manufacturers pro
104. lar moni toring It is not a comprehensive list of problems that can occur with your specific drip irrigation system Monitoring Soil Moisture Soil moisture measurements should be made at the following times Before the first use of the system to determine field capacity see PLANNING Field capacity After the first few irrigation cycles to verify your irrigation schedule and to make necessary adjustments Periodically throughout the season to make schedule adjustments as the water requirements of your plants change Soil moisture content and tension Most commercial moisture sensors provide a reading either of tension matric potential or moisture content Tension is a measure of the work a plant must do to remove water from the soil and is usually expressed in bar or centibar 1 bar 100 centibar The drier the soil is the more work plants must do to remove water and the higher the tension Tension is a useful measurement since it is the aspect of soil moisture that directly affects your crops Moisture content is a measurement of the water contained in the soil as a percentage of the volume of the entire soil solution Moisture content can directly indicate how much water you need to apply at the root zone to return it to field capacity Sensor placement Measure soil moisture at several depths and locations in the field With a portable moisture sensor you can accomplish this by taking a number of measurements with the same s
105. less water to some parts of the field and more to others Drip irrigation can deliver very high uniformity and this is one of the keys to its high potential efficiency A well designed drip system can achieve DU of 90 or higher RO DRIP is manufactured Poor distribution uniformity leads to non uniform crop growth and poor irrigation efficiency Poor uniformity can be caused by The Roberts Difference with an advanced high pre A EE A cision process that results Drip emitters becoming plugged with dirt algae or other material Pressure variations caused by uneven terrain in an emitter coefficient of Pressure variations caused by friction losses vacation alvin ae e Excessive drip tape run lengths I e Use of poor quality drip tape This translates to better All of the above factors can be controlled with careful design and management dd ll and I Ia q ai A u higher irrigation efficiency Drip Emitters and their Effects on Distribution Uniformity fig 3 2 A drip tape emitter consists of an inlet a flow channel and an outlet The inlet allows water in your field into the flow channel from the main chamber of the drip tape The flow channel is a narrow path with a complex shape designed to slow down the flow of water and create turbulence which prevents contaminants from settling The emitter outlet is a small opening at the end of the flow channel through which the water drips into the soil A well engineered emitter doe
106. lter back flushing automatic Ave yield 500 boxes acre 1235 per ha Duration of tape installation 60 days Drip Tape RO DRIP 5 12 24 5 mil 12 in spacing 24 GPH per 100 ft 5 8 in diameter 127 mm 30 cm spacing 298 LPH per 100 m 16 mm diameter RO DRIP USERS GUIDE B 5 B 6 CROP PRODUCTION Celery Celery is usually transplanted on single row 24 to 30 in 59 to 76 cm beds or double row 32 to 40 in 81 to 102 cm beds In double row plantings rows are spaced 10 to 12 in 25 to 30 cm apart with a singe drip lateral on or near the surface between the plant rows Plants are spaced 7 to 10 in 18 to 25 cm apart within each row Celery is a biennial that normally produces foliar growth in the first year and seed stalks in the second year However celery plants can form seed stalks bolt the first year if exposed to temperatures below 55 F 11 5 C for 7 days or longer Some varieties are more susceptible to bolting than others Celery planted early in the year in cooler climates is usually covered with plastic tunnels to increase daytime temperatures and prevent induction of bolting by low night temperatures Celery is a shallow rooted crop most roots are in the upper 18 in 45 cm of soil It is therefore very susceptible to drought Hot dry periods without water reduce growth and may induce blackheart EXAMPLE Celery a Baja California Mexico J Y Y 40
107. micals to prevent plugging of the drip tape emitters For example chlorine and or acid may be injected to kill microorganisms and to prevent precipitation of dissolved minerals Chemical treatment may also include injection of pesticides herbicides or systemic fungicides to improve the health of your crops or gypsum or acid to improve the physical characteristics of your soil MANAGEMENT Water Treatment describes how to use chemical injection to prevent emitter clogging by organic matter and precipitates Caution all personnel who use or otherwise come in contact with fertilizers and chemicals should be thoroughly trained and qualified in the safe and effective storage use and application of these potentially dangerous substances Fertigation One of the outstanding benefits of a well designed drip irrigation system is the ability to precisely control the nutrient environment in the root zone of your plants for optimum yield and quality Drip fertigation can apply N P K and minor nutrients exactly where and when they are needed throughout the season To take advantage of this high level of control it is necessary to closely monitor the nutrient level in the soil and plant tissue and make adjustments as necessary Determining nutrient requirements Before installing your drip irrigation system have a soil sample tested to determine its nutrient content This should include nitrogen phosphorus potassium and minor nutrients The nutrient re
108. mportant and can improve crop response to essential nutrients while using less fertilizer than traditional irrigation methods Drip fertigation can also efficiently fertilize crops that are covered by plastic mulch Injection Methods Locate injection equipment downstream of your pump and upstream of your filters which aid in mixing and can prevent emitter plugging due to particulate buildup or chemical precipitation The only exception to this rule is strong acids which may corrode filter components and should be placed downstream of the filters Caution Serious plugging can occur to drip tape from unpredictable mixing of your water fertilizers and chemicals that may form precipitates Always inject fertilizers and chemicals before the filters and know how they will react Have a water quality analysis performed to help you recognize and address potential incompatibilities RO DRIP USERS GUIDE DESIGN When specifying and or installing injection equipment always do the following Include a backflow prevention device to prevent backflow of chemicals into the water source and a check valve to prevent flow of irrigation water into chemical tanks Use injector pumps and components that resist corrosion from fertilizers and acids If using an electric injection pump include an interlock circuit to ensure the injection pump automatically turns off when the system pump shuts down Select an injector that is easy to operate and ad
109. ms irrigate several times a week or even several times a day In addition because drip irrigation promotes more localized root growth even a short lapse in water availability can cause serious crop damage It is important to confirm that your water source will be available whenever you need it throughout the growing season If necessary arrange for a supplementary water source that can be used in the event that your primary source becomes unavailable If a supplementary water source is required confirm that your system design includes filtration appropriate for the additional water source WATER QUALITY Water quality refers to the physical and chemical composition of your irrigation water It has important effects on the type of filtration to use chemical water treatment that may be necessary the frequency of cleaning and line flushing and the management of salt and chemical buildup in the soil The effect of water quality on your system s performance should not be underestimated System designs that do not account for the quality of their specific water source can become completely debilitated by emitter plugging and can result in serious crop damage These problems can be easily prevented through proper filtration and or water treatment Before designing your system order a complete physical and chemical analysis of your water source This analysis should quantify the amounts of the following matter commonly found in water sources Physic
110. nces in individual drip systems most have the components advanced emitter design shown in figure 31 which delivers unparalleled Components of a Typical Drip Irrigation System see fig 3 1 discharge uniformity and resistance to plugging 1 System controller 4 Fertilizer injector tank 2 Pump 5 Filter tanks 3 Back flow prevention valve 6 Butterfly valve or ball valve 20 20 Figure 3 1 Components of a Typical Drip Irrigation System 3 2 RO DRIP USERS GUIDE DESIGN 7 Pressure gauges 14 Submain secondary filters 8 Mainline control valve 15 Pre set pressure regulator 9 Mainline 16 Submain 10 Flow meter 17 Lateral hookups 11 Air vents at high points after 18 Laterals valves and at ends of lines 19 Flushing manifolds 12 Pressure relief valve 20 Flush valves 13 Field control valve IRRIGATION EFFICIENCY What is Irrigation Efficiency The Irrigation Efficiency IE of your system is a measure of the proportion of water used for intended purposes If your system is 90 efficient then 90 of the water it applies is used by your plants or for other intended purposes and 10 of the water is not used productively Irrigation Efficiency is affected by both the design and management your irrigation system Distribution Uniformity Distribution Uniformity DU is a measure of how uniformly your irrigation system applies RD3 2 water to all parts of your field A non uniform irrigation system delivers
111. ned filtration system is used fine silt and clay particles can get past the filters and settle in the laterals If they are allowed to build up they can eventually plug emitters and damage the system In multiple year subsurface applications the system should be run with the ends of the laterals open after each season in order to flush these particles out In areas where water quality is a problem lateral flushing may be required more often Systems using extremely dirty water may require flushing as often as every 2 weeks or even after each irrigation Paying extra attention to prevention of plugging is always less costly than having to replace an entire system once it becomes plugged Flush laterals by opening the ends and running the system until the discharge water runs clear Opening the ends is easier if removable end caps or flushing manifolds were specified in the design stage fig 5 2 The flow velocity at the end of each lateral should be at least one foot per second 0 3 meters per second which is achieved with a flow rate of 1 GPM 3 8 LPM at the end of each 5 8 in 16 mm lateral or 2 GPM 7 6 LPM at the end of each 7 8 in lateral A rule of thumb that has been successfully used by many growers is that a stream of water should squirt 2 to 3 feet from the end of the lateral You can flush several laterals simultaneously as long as your water supply capacity is sufficient Clearing clogs if they occur You can almost always avoid emitt
112. normal irrigation 46 or 61 cm Actual depth may vary depending on crop type and rooting depth Monitoring Soil Salinity Even with low salinity water salt can accumulate in the soil unless some leaching occurs In addition to the salts that are part of almost all irrigation water fertilizers can also add to salt content Relatively low concentrations can damage some crops by making the soil water less available to the plant root system By the time the effects of salinity are actually seen in the plants damage to yield has already occurred In problem areas periodically send samples of the soil solution to a lab for analysis of salt concentration Several commercial EC sensors are also available that can give reasonably accurate results in a short amount of time MAINTENANCE Maintenance of your drip irrigation system is critical Drip systems require more diligent attention than other forms of irrigation and failure to properly maintain all components can lead to system failures that result in expensive repairs or even crop damage The purpose of most maintenance functions is to keep emitters clean although other functions such as pest control and repair of damaged laterals are also important Keeping the emitters clean Great care must be taken to prevent drip emitters from plugging with dirt organic matter or precipitates A slight plugging problem will eventually result in greatly reduced distribution uniformity A serious pluggin
113. nters Germinating lettuce in hot weather can lead to thermodormancy of the seed and irregular stands Keep the soil around the seed moist during warm weather germination to provide cooling and start the germination process in the evening so the seed imbibes water during the coolest part of the day Plants are thinned to an in row spacing of 8 to 12 in 20 to 30 cm depending on the type of leaf lettuce Plant spacing and fertilization can be varied to control head size EXAMPLE I Lettuce Baja California Mexico Yi ll s 40 Operation Auxiliary Equipment CHOP eee Hom bu haapa Sete lettuce Primary filtration sand separator Location Baja California Mexico Secondary filtration screen Field size 90 acres 36 ha SUDMAING ea lames made cis layflat Plants per acre 37 100 91 600 per ha MUD 5420398 5A 44 ie ters TEETE none SEASON e A E TA Apr Aug l Planting method direct seeded Management Operation Soil type ieres sandy loam Irrigation frequency 3 5 days Maximum ET 0 35 in 9 mm per day Irrigation duration 4 10 hours Water Source deep well Chemigation yes Groundcover OMC NertigalloN sonno aaa s Lesa daai yes Crops rotated with broccoli cauliflower 1 ine flushing at startup Time to maturity 50 60 days Fi
114. oil laterals should be placed as close as possible to the plants See MANAGEMENT Germinating Seeds Spacing between laterals The spacing between laterals is determined to a large extent by the distance between centers of your crop rows Depending on your soil type and ET requirements however it may be possible to irrigate more than one row with each lateral resulting in reduced system cost and lower application rates Other combinations such as using three laterals to irrigate a four row bed are also possi ble In such cases it is important to be sure that the edge of the wetting pattern from each lat eral does not coincide with the position of the plant row Salts that accumulate at the edge of the wetting pattern can damage or kill plants To calculate the total length of drip tape L which will be required to cover your field at a given spacing between laterals use the following formula Sandy Soil Clay Soil Figure 3 3 Lateral Placements number of acres x 43 560 L feet o x number of tape rows per bed bed spacing in feet or number of hectares x 10 000 L meters F gt T D x number of tape rows per bed bed spacing in meters RO DRIP USERS GUIDE DESIGN If your field is flat set number of tape rows per bed to 1 and use the lateral spacing in place of bed spacing above Surface vs subsurface depth of laterals There are four common methods of depth placement for drip ta
115. ontaminants from entering the water supply They should be installed in drip systems that are used for RO DRIP USERS GUIDE 3 19 3 20 DESIGN chemigation and or fertigation and are required by law in many areas Instrumentation The two most important devices for measuring water movement between the water source and your field are flow meters and pressure gauges Close monitoring and accurate record keeping with these devices will allow you to make the most fundamental adjustments to your system operations and detect problems before they can have serious effects on your crop Flow meters Flow meters allow you to directly measure application rates and can help you detect problems such as clogging or line breakage Install at least one flow meter on the main supply line to indicate the total amount of water being applied to the field Read this meter and record the information for the new system a regular basis thereafter Flow meters are available that show total and instantaneous flow rates There are several types of flow meters to choose from the most popular being the propeller type flow meter due to its reliability and low cost The reliability of flow measurements is highly dependent on the flow meter location Propeller flow meters should be located downstream from a straight unobstructed length of pipe at least eight times the diameter in length For accurate readings the pipe must flow full Pressure gauges The
116. ost of the growing season is to maintain this level by replacing soil water as it is lost to evapotranspiration With some adjustments to account for local weather minor crop differences salinity and system inefficiency you can develop a good prediction of water requirements the right choice when water Note Applying more water than is needed can increase root disease and operating cost while applying less than needed can stress or burn your crop and cause your soil to dry destroying its ability to move water A properly designed and managed irrigation system will deliver just enough water to maximize both yield and profit Field Capacity Field capacity is an estimate of the amount of water that is held by the soil after it has been completely drained by gravity Field capacity is dependent on soil type and represents optimum soil moisture conditions for most crops because of its ideal balance between aeration and available water In order to keep soil moisture conditions ideal for crop growth you must be able to determine when your soil is at field capacity If you have a moisture sensing device available you can obtain a quantitative measurement of field capacity with the following procedure 1 Determine the proper monitoring depth for your crop 2 Prepare the field and install the moisture sensor at the proper depth More accurate results can be obtained by installing 4 sensors in a 10 x 10 ft 3 x 3 m test area 3 Irrigate un
117. ould be included at low points and at the end of lines but also at any other point that can be subjected to large pressure surges RO DRIP USERS GUIDE DESIGN Table 3 11 Lateral Connections to Submains se ona Simple and reliable only one fitting per lateral Direct connection via k ka Twist Lock fitting Most common in surface applications eIn subsurface applications laterals must be buried at the same depth as submains Allows surface placement of laterals with buried submains tube using fittings e Small diameter transfer tubes may result in pressure losses Requires up to two fittings and a transfer tube for each lateral Connection via transfer Lowest cost method of connecting a lateral to a submain Small diameter transfer tubes may result in pressure losses Greater risk of leaks Connection via transfer tube without fittings Field control valve A field control valve is usually included at the beginning of each submain Gate valves but terfly valves and globe valves are commonly used and field control valves may be automatically controlled Field control valves are usually used as on off valves with in line pressure regulators or pressure reducing valves used to control the pressure in each submain Mainline control valve Control valves used on mainlines may be simple on off valves or may be used to partially restrict flow or reduce pressure Gate valves and butterfly valves are commonly used with globe
118. pe e Surface placement on flat ground e V Ditch placement e Shallow sub surface 1 4 in 2 5 10 cm Deep sub surface deeper than 5 in 13 cm Depending on your specific situation and crop any of the above placement methods may be appropriate Table 3 2 presents some typical applications for each NOTE When drip tape is installed deep enough that the wetted area does not reach the surface salt buildup may occur just under the surface of the soil This can create a situation in which rain can leach salt into the root zone and stress or even kill the crop Refer to MANAGEMENT Managing Soil Salinity for information on managing salt buildup NOTE Depth of laterals is critical if they are used to germinate crops Depending on soil type deep subsurface laterals may not be able to supply the water to the surface required by the seeds In such cases sprinklers are required fig 3 4 Raised beds Raised beds are not necessary in drip applications However they should be considered where salinity or drainage around the plants is a serious problem Raised beds can also facilitate harvesting of short stature crops such as strawberries Finally raised beds can increase soil temperature resulting in increased yield and earlier harvest Where possible consider a large bed width of 60 or 80 inches 150 200 cm and use 2 drip laterals per bed to increase the percentage of production area and yield potential NOTE When two laterals are use
119. pe users in multiple season applications 8 mil 0 200 mm first ume drip pe users experienced drip tape users in multiple season applications LO mil 0 254 mm portable applications may be relocated e multiple year buried applications portable applications may be relocated 13 mil 0 325 mm multiple year buried applications maximum resistance to pests and mechanical damage Selection of Wall Thickness Drip tape products are available with a variety of wall thicknesses ranging from 4 mil to 25 mil The thinnest walled products are lower cost but are more susceptible to mechanical and pest damage They are typically used in single season applications by experienced growers The thick er walled products are more resistant to damage and can be used for multiple seasons Their higher tensile strength also makes them well suited for retrieval and re installation in the field See table 3 6 for general guidelines on selecting wall thickness portable applications may be relocated e multiple year buried applications maximum resistance to pests and mechanical damage Run Length and Selection of Diameter For a given flow rate larger drip tape diameters allow longer lateral runs The standard diameter of most drip tape products is 5 8 in 16 mm Most manufacturers also offer larger diameter drip tape for applications requiring extremely long lateral runs RD3 12 Table 3 7 Considerations for Selecting Drip Tape Diameters FEA
120. percent of ground covered by your plants If the resulting number is less than 0 2 use a value of 0 2 Calculate the percent ground coverage as the distance across the bed that is covered by the crop divided by the bed spacing times 100 For example cucumbers early in the season which cover 50 of the ground surface will have a crop coefficient of 0 5 x 0 9 0 45 Table 5 1 Estimated Peak Crop Factors for Various Plants ESTIMATED PEAK CROP FACTORS Re FOR VARIOUS PLANTS Cabbage 95 Pepper 95 Cantaloupe 95 Potato 1 05 arrot 1 00 Strawberry with plastic mulch 1 05 Celery 1 00 Strawberry without plastic mulch 1 10 Cotton 1 05 Sugar cane 1 05 Corn 1 00 Squash 90 Cucumber 90 Tomato 1 05 Lettuce 95 RO DRIP USERS GUIDE MANAGEMENT If you do not find your crop in table 5 1 you can estimate Kc as the percentage of ground covered Both crop coefficients and reference ETo values are now available on the Internet for many areas These web sites provide both real time and historical information and can be very useful design and management tools If a reference evapotranspiration ETo rate is not available for your area use a potential Table 5 2 Potential Evapotranspiration PET POTENTIAL EVAPOTRANSPIRATION PET Cool humid Cool dry Warm humid Warm dry Hot humid Hot dry evapotranspiration rate PET from table 5 2 as an approximation of ETo Developing and Maintaining a Proper Wetted Area In genera
121. proper levels and avoid plant stress which can easily go unobserved Flood or sprinkler irrigating between crops can be very effective in removing salts and may be necessary in some cases Apply excess water for leaching early in the season since it may be difficult to apply adequate water during the peak of the irrigation season Multiple Row Beds In many cases you can save money by irrigating more than one crop row with each lateral In multiple row beds however be careful not to place a row directly between two drip laterals The salts at the edge of the wetted pattern of each lateral can accumulate under the center row and can damage or kill salt sensitive plants Figure 5 6 illustrates proper and improper methods of avoiding salt buildup when irrigating multiple rows with a lateral Figure 5 6 Proper and Improper Placement of Laterals for Multiple Rows MANAGING SOIL PERMEABILITY Soil permeability is affected by texture structure organic material content and chemical content Good soil preparation and addition of organic amendments can reduce permeability problems caused by compaction Several permeability problems are caused by the quality of your irrigation water and can often be avoided through chemical water treatment or chemical soil amendments The first step in managing permeability is to have a chemical analysis of your irrigation water performed Table 5 10 shows how to manage certain water quality problems that can l
122. quirements of the drip irrigation tape Seasonal or other changes in potential contaminants Potential for precipitation of dissolved solids due to chemical reactions Consultation with a qualified irrigation specialist Table 3 10 summarizes the filter types and their proper use PUMPS There are a variety of pump types available Each has a performance profile represented by a pump performance curve Pump lift capacity and discharge pressure are all factors to consider The particular balance of these factors will be determined by the pressure and flow rate required by your system and by the type and location of your water source RO DRIP USERS GUIDE DESIGN Table 3 10 Filter Types Filter Type Application Specifications Notes Sand Media Filter Screen Filter Centrifugal Sand Separator Gravity Flow Filters Disc Filter Suction Screen Filter Settling Pond Required for any open or surface water source where large amounts of organic matter are pre sent Frequently used for well water Usually a secondary fil ter as a back up for a media filter May be used as a primary filter for very clean water sources Used to remove sand well casing and other inorganic material Can be used as a pre filter to reduce backflushing of main fil ters For low or medium levels of particulate Used to deliver a large volume of water at a low pressure Primary filtration Used in m
123. quirements of your plants change throughout the season and your fertigation program should reflect this If possible obtain data on the nutrient requirements of your crop at each growth stage In combination with tissue testing throughout the season see MANAGEMENT Fertigation this information will allow you to maximize the efficiency of your fertigation program EXISTING INFRASTRUCTURE Installing a drip irrigation system inevitably requires changes in equipment training and cul RO DRIP USERS GUIDE PLANNING tural practices However a new system design does not always require completely new infra structure In fact a good system design should identify and make use of as much existing infrastruc ture as possible such as the existing water source distribution systems electrical supply and access roads PLASTIC MULCH The term plasticulture refers to methods of growing under plastic using drip tape Drip irrigation is uniquely suited to cultural practices that use plastic mulch For some crops the combination of drip tape and plastic mulch results in optimum yield and water usage through improved control of soil temperature and moisture level While growing under plastic has been a barrier to water delivery using traditional sprinkler and furrow irrigation plastic mulches and crop tunnels do not present a problem with drip irrigation Plasticulture is used for a number of reasons including Control of soil temperature e
124. r drip system Repairing Damaged Laterals Laterals that are damaged by pests equipment or inexperienced field workers can be repaired by cutting out the damaged portions and splicing the ends together This can be done with twist lock couplings or with polyethylene hose and wire ties as described in INSTALLA TION AND STARTUP Splicing Laterals System Shut Down Between Crops multi season subsurface When a drip system is shut down between crops extra maintenance is required to kill the RO DRIP USERS GUIDE MANAGEMENT roots of the crop If the roots of the previous crop are not killed they will seek the water remain ing in the laterals and may plug emitters making them unusable in the future In addition later als should be opened and thoroughly flushed at the end of each season If you plan to use your laterals for more than one crop use the following procedure to shut down your subsurface drip irrigation system at the end of each season Follow the procedure whether the laterals are permanently installed or are to be removed and re installed 1 As soon as the crop is no longer in production inject a soil fumigant to kill roots around the drip tape to prevent root intrusion 2 If algae is present in the system inject chlorine at a concentration of 50 ppm superchlorination If algae and mineral deposits are both present inject a concentration of acid that is sufficient to lower the pH to 4 0 at the ends of the lateral
125. r concentrations if the organic material content of the irrigation water is high Use higher concentrations of chlorine if the pH of the water is 7 5 or greater or lower pH by injecting acid To eliminate severe algae growth consider using a one time superchlorination of up to 50 ppm for 4 6 hours at elevated pressure and pH below 6 5 followed by thorough flushing with clear water Chlorine is more effective at killing algae and bacteria when the pH of the water is 6 5 or lower Alkaline water should be acidified for effective chlorination see Acid Injection below NOTE Always inject chlorine and other chemicals upstream of filters to avoid problems from chemical precipitation and to clean filter elements CAUTION Inject acid and liquid chlorine through two different injection ports Mixing acid and chlorine in the same tank will release dangerous chlorine gas Acids and chlorine should never be mixed together Acid Injection It may be necessary to add acid to irrigation water to lower its pH to prevent the precipitation of calcium carbonate CaCO3 calcium phosphatic compounds or iron oxides Fe2O3 that can plug emitters In addition low concentrations of acid can increase the effectiveness of chlorine in alkaline water The three acids generally used are sulfuric muriatic and phosphoric Extra care RO DRIP USERS GUIDE MANAGEMENT should be taken when using phosphoric acid because precipitation of minerals in the wat
126. r functioning 41 4 2 INSTALLATION AND STARTUP Table 4 1 summarizes several important guidelines for proper installation Table 4 1 Installation Guidelines eStore drip tape in a protected area and leave wrapping in Begin installation before carefully planning and place until ready to install engineering your system Prepare soil and beds before planting Particle size should Step on laterals or drag drip tape across soil surface be small and uniform Apply uneven tension or jerks that can stretch tape and alter Install laterals with emitters facing up flow rates Maintain a low constant tension on drip tape roll Handle drip tape using any tools or equipment with burrs or Test the system before irrigating other sharp edges Note Always install tape with the emitters facing up in both surface and subsurface applications This prevents sediment from settling to the bottom of the tape and clogging the emitters INSTALLING DRIP TAPE LATERALS Manual Tape Installation Manual drip tape installation is common in small fields and greenhouses where laterals are placed on the surface because it is often the most cost effective choice Manual installation is less practical in large fields or in subsurface applications It is generally not practical to manually install deep subsurface drip systems Use PVC vinyl layflat or poly hose for submains If using PVC submains above ground protect them from sunlight with a lig
127. r to open the bed down to a depth of 2 3 in 5 7 cm above the lateral and pull the tape through the remaining soil in the same operation Retrieval is easier if the drip tape was installed accu rately at the beginning of the season A reli able and consistent burial depth allows you to place the opening tool close to the buried lateral and minimize the amount of soil through which it must be pulled Retrieval is simpler if the soil above and around the laterals is loosened and softened beforehand If possible turn the last crop and wait a few days for subsurface plant matter to decompose and soften Immediately before retrieval soften the soil around the laterals by irrigating for a period of time Disrupt the bed on either side of the laterals with picks or chisels RO DRIP USERS GUIDE 6 5 UNDERSTANDING YOUR WATER QUALITY REPORT UNDERSTANDING YOUR WATER QUALITY REPORT The following tables summarize the information that may be presented in your water quality report and give guidelines to help you interpret how it will affect your operations Table A 1 Quantities Measured in Your Water Quality Analysis Determination Symbol Units Typical Range SALINITY Total Salt Content Electrical Conductivity or Total Dissolved Solids Specific lons Calcium Magnesium Sodium Carbonate Bicarbonate Chloride Sulfate Nitrate Nitrogen Ammonium Nitrogen Phosphate Phosphorus Potassium Kt ppm MISCE
128. ral operations Reduced pest damage Improved water move ment Reduced weed growth Prevents damage from clear plastic coverings Can be used for several seasons with out retrieval Reduced damage from cultural operations Reduced pest damage Reduced weed growth Reduced loss to evap oration Advantages Disadvantages Increases risk of mechanical damage Tape may wander due to heat or wind Surface wetting increases weed growth and may promote disease eIncreases runoff in heavy soils Increases evaporation More exposure to damage than with sub surface place ment Increased weed growth Increased evaporation More difficult to visu ally detect damage Salt accumulates just below the soil surface and may be carried into the root zone by rain More difficult to repair damaged tape Installation equipment required Sprinklers may be required to germinate crops or to leach salt from the root zone Requires anchoring of tape eShould not be used with clear plastic cov erings to avoid burn ing or overheating of tape A compromise between the charac teristics of surface and shallow sub surface placement Mechanical or manual installation is possible Common with plastic mulch Usually requires mechanical installa tion via tractor and toolbar Rodent and insect problems are greatest in new fields where adequate control measures have not
129. rding better and more frequent information on your crop status and water quality moni toring system performance and making minor adjustments whenever needed Fortunately there is now a full line of products know how and automation equipment available to help you in this process While drip irrigation can deliver significant savings on labor and resources you should expect some increase in management time especially in the first year as you learn to operate the system There is no substitute for a competent farm manager who fully understands the drip irrigation system and is available to make adjustments as needed USING THIS GUIDE This guide covers all the basic requirements for drip tape irrigation in row crop nursery and greenhouse operations It has been written to be a useful reference for almost any drip irrigation question you may have regardless of what drip tape you decide to use However since Roberts Irrigation considers RO DRIP the most advanced and cost effective drip tape available special sections are included that describe features and requirements unique to RO DRIP and RO DRIP XL wherever applicable NOTE This guide is intended to provide information about RO DRIP and generally accepted knowledge in drip irrigation and crop production Roberts Irrigation Products Inc is not engaged in rendering engineering hydraulic agronomic or other professional advice in this guide Consultation with qualified local irrigation de
130. re usually direct seeded on four row beds spaced 42 in 106 cm between centers Rows are spaced 6 to 12 in 15 to 30 cm apart with 1 to 4 in 2 5 to 10 cm in row spacing Spacing is closer and populations are higher for smaller bulbing varieties Onions are extremely shallow rooted and need an easily crumbled medium texture soil that maintains moisture well Onions should never be stressed for water once bulbs start to enlarge or splitting may result Avoid salty hard or weed infested soils In the example below the grower used a short row length of 328 ft 100 m Using RO DRIP 8 12 24 good uniformity can be maintained with run lengths of up to 800 ft 250 m on flat ground EXAMPLE P Fresh Market Onions Baja California Mexico Y Za vy WY M i 8 43 22 lt 40 Operation Auxiliary Equipment Chopin ha tae bea tee fresh market onion Primary filtration sand separator Location Baja California Mexico Secondary filtration screen Field size 150 acres 60 ha SUDMAING J yaa g ua yaaa ga layflat Plants per acre 197 885 488 975 per ha MUNCH varat 20479 300 0040 0 3100 3310 486 none Season Feb March f Planting method direct seeded Management 0peration Soil type Stes sandy loam hrigation duration 4 10 hours Maximum ET 0 35 in 9 mm per day Irrigation frequency
131. rect ly into drip irrigation systems Only apply a fertilizer through your drip system after testing its compatibility with your local irrigation water see Jar Test below Water Soluble Dry Fertilizers Non liquid fertilizers must be mixed with water to form a solution before they are injected Dry fertilizers must be water soluble and it is necessary to consider how they will react with the minerals contained in your water or other fertilizers which are injected a common problem is phosphate reacting with calcium to form a precipitate Only apply a fertilizer through your drip system after testing its compatibility with your local irrigation water see Jar Test below NOTE Some dry fertilizers which are described as being water soluble are coated with clay or wax to prevent clumping This coating material is not water soluble and can plug filters and drip emitters It can be removed through a decanting process by thoroughly mixing the fertilizer with water and allowing it to settle for 12 18 hours Pour the clear solution through a 200 mesh screen taking care not to allow the sediment or precipitate to enter the system Jar Test Performing a simple test of your irrigation water and fertilizer mixture before injection can help you avoid the high cost of cleaning or replacing your drip system if precipitation occurs fig 5 4 Perform a jar test as follows 1 Fill a clear 1 quart liter glass container with your irrigation wa
132. resource and agricultural agencies ET is affected by Local climate e Crop type Size of leaf canopy Stage of growth cycle Ground cover Size of wetted area Research has shown that for vegetative crops yield is generally proportional to transpiration For given weather conditions transpiration is maximized when the water content in the root zone is near field capacity at all times Therefore it is important that as water leaves the root zone as a result of ET your irrigation system is able to replace it as soon as possible The ability to keep the root zone near field capacity at all times is an important benefit of drip irrigation To realize this benefit your system design must be capable of supplying water at the rate of ET at all times during the growing season You can anticipate what peak demand will be by referring to historical ET data and use this information to design a system that can supply enough water under any conditions If ET information is not available for your area refer to MANAGEMENT Scheduling Determining your crop s daily requirement for methods of estimating ET Flushing Requirement Since filtration cannot remove all contaminants silt and clay may settle in drip laterals and if not removed may build up and plug emitters In areas where water quality is a problem or when drip tape laterals will be used for multiple growing seasons your system design must allow for periodic flushing of the laterals If
133. rigation manufac tures several low flow rate products with wider emitter spacings which are special ly designed to form good wetted patterns in heavy soils with high clay content These include 12 in 15 GPH RO DRIP 30 cm 186 LPH 16 in 10 GPH RO DRIP 41 cm 124 LPH and 24 in 17 GPH RO DRIP 61 cm 211 LPH 5 3 5 4 MANAGEMENT Table 5 3 The Effect of Wetted Area on Crops Small Wetted Area Large Wetted Area Restricts roots to a small volume of soil Wastes water and fertilizer Reduces uptake of needed minor nutrients from soil Increases the number of weeds Increases potential for plant water stress during Does not improve crop performance periods of high temperature and wind Ideal Wetted Area The ideal wetted area is shaped as shown Sandy Soil Clay Soil The wetted area should be maintained at the same size I throughout the season to prevent salts near the edges from damaging the crop Soil type and field preparation affect the shape of the cross section dramatically irrigation that will apply enough water to replace evapotranspiration ET and compensate for system inefficiency see DESIGN Irrigation Efficiency Use the following steps to determine the proper irrigation duration 1 Estimate the amount of water used by your crop between irrigation cycles by multiplying the daily ET rate see Determining you crop s daily requirements in this section by the number of days between irriga
134. rminate seeds in light soils Sugar cane Some vegetables provides lower flow rate for improved infiltration of heavy soils Corn 24 inch very long runs are possible Cotton may not effectively germinate seeds in light soils Sugar cane General guidelines only Actual spacing will depend on soil type run length and other specifics of your operation Selection of Flow Rate As illustrated in the previous section drip tapes with narrow emitter spacing deliver higher flow rates due to the larger number of emitters per unit of length In addition many drip tape products are available with two flow rates for each emitter spacing referred to as Standard Flow and Low Flow products Table 3 4 provides a comparison of Standard Flow and Low Flow emit ters Examples of Standard Flow and Low Flow RO DRIP products are given in table 3 5 Consult the RO DRIP Product Data Sheets for a complete listing of flow rates and emitter spacings When you select a drip tape flow rate emitter spacing and lateral spacing you need to ensure that during irrigation The system does not require a higher flow rate than your water supply can provide e The system can sustain the application rate required by your field RO DRIP USERS GUIDE 3 9 3 10 DESIGN Table 3 4 Standard Flow and Low Flow Emitters EMITTER FLOW RATES FEATURES provides a better wetting pattern in some light soils Standard Flow higher application rate for a
135. s 3 Allow the chlorine or acid to remain in the system for 4 6 hours 4 Run the system for at least 1 hour with clear water 5 Open the ends of the laterals and flush the system thoroughly or open the flushing valve if a flushing manifold is used 6 Close the ends of the laterals GERMINATING SEEDS The successful use of your drip irrigation system for seed germination depends on your soil texture soil structure soil salinity the depth of your laterals the emitter spacing and the prepa ration of your beds To germinate seeds enough water must reach the surface for the individual seeds or plants to receive water In addition salt buildup must be kept away from the seeds or plants Drip tape can generally be used to germinate seeds of salt tolerant crops under the following conditions The laterals are less than 8 in deep e The emitter spacings are 12 in or less e The soil is not excessively coarse or sandy e Salinity is not a major problem The seedbed is uniform and clod free several inches deep Conditions are further improved if there is at least 6 in 15 cm of effective rainfall per year to leach salt away from the surface When using drip tape to germinate a crop irrigate frequently enough and with adequate run times to assure that near field capacity conditions are maintained around the seed at all times Over irrigation however can lead to fungal disease and damping off of seedlings If laterals are buried
136. s Consider using the 25 rule of fertilizer injection During the first 25 of the irrigation cycle only clear water is delivered through the laterals Fertilizer is injected for the next 50 of the cycle then clear water is again used for the final 25 Note Always inject fertilizers into the water stream before the filter Note Only inject fertilizer if a proper backflow prevention device has been installed upstream of the injector to prevent flow of fertilizer into the water source Monitoring Nutrients Drip fertigated fields require less fertilizer than those using sprinkler or furrow irrigation Fertilizer is only applied to the root zone and used as efficiently as possible Drip fertigation allows you to optimally use your fertilizers by adjusting the application rates throughout the season as the needs of your plants change To take full advantage of this feature you will need to know the nutrient levels of your soil and plants throughout the season to make the necessary RO DRIP USERS GUIDE 5 15 5 16 MANAGEMENT adjustments The first step in determining which nutrients to apply and how much of each to apply is to have a soil test performed at the beginning of the season Use your drip system to make up the difference between what is available in the soil and what your plants need Additional information such as the soil pH EC and base saturation will help you determine which fertilizers can be readily used b
137. s increasingly scarce Any steps that can be made to reduce this trend will have a long term positive impact on the environment Re use Several steps must be taken to ensure that drip tape intended for re use is in good condition at the beginning of each season For best results when re using drip tape observe the following important guidelines e Follow a proper shutdown procedure see MANAGEMENT System Shutdown Between Crops to ensure the drip tape is clean and free of roots bacteria and algae before it is removed from the ground RO DRIP USERS GUIDE RETRIEVAL Avoid jerking or excess tension while retrieving drip tape from the ground Any stretching of the drip tape will result in uneven flow rates and decreased distribution uniformity Always store drip tape in a dry pest free protected area RD6 1 Retrieval for re use is a more delicate process than retrieval for disposal In general it is easier The Roberts Difference to retrieve thicker gauge drip tape without damage Use a great deal of care when retrieving any tape less than 10 mil thick When drip tape is retrieved for re use it should be rolled onto a suitable spool Commercial includes several heavy plastic spools are available for retrieving drip tape Many growers choose to make their own spools by placing wood or metal side plates on the ends of a large diameter section of PVC pipe which acts as the core of the spool When the roll is full the side plates
138. s three things very well It emits water at a predictable and consistent rate It emits water at nearly the same rate for a range of supply pressures e It resists plugging Two important numbers quantify how well a drip tape emitter does its job the Coefficient of Variation Cv and the Discharge Exponent x Most drip tape manufacturers publish Cv and x values for all of their products or will provide them upon request Several independent test labs also rate emitters and publish this information See appendix C for definitions of Cv and x and explanations of how they affect system performance raised root deflector turbulent vortex expanding flow dual water inlets channel top outlet orifice flow channel molded into RO DRIP Figure 3 2 Anatomy of a Drip Emitter RO DRIP USERS GUIDE a3 RD3 6 The Roberts Difference The RO DRIP emitter has a unique expanding flow channel which can open up to pass trapped debris If a clog occurs it can often be removed by temporarily increasing the supply pres sure until the expanding flow channel flexes open and allows it to pass RD3 7 The Roberts Difference The comprehensive RO DRIP product line pro vides a broad selection of wall thickness emitter spacing flow rate and diameter that will allow you to select the right drip tape for your application RD3 8 The Roberts Difference The adv
139. select a drip tape with a low Cv Table C1 gives an idea of Co values you can expect and what they mean Table C1 Emitter Cv Values and their Classification lt 0 05 Excellent 0 05 0 07 Good 0 07 0 11 Marginal gt 0 11 Poor As designated by American Society of Agricultural Engineers ASAE EP405 1 DEC94 It is important to realize that the Co values published by manufacturers are for new product and that long term performance of your installed drip system can be as much affected by how well the emitters resist plugging as by the Cg Emitter discharge exponent the x factor When a drip tape emitter is operating at its recommended pressure it generally discharges water at its published rate with minor variations resulting from its Cv If you increase pressure from that point the discharge rate will increase If you decrease pressure the discharge rate will decrease The quality of the emitter determines how much the discharge rate changes in response to pressure changes The Discharge Exponent x of an emitter is a measure of how much its discharge rate varies as supply pressure varies An x of 1 means that the discharge rate varies directly with pressure Le if supply pressure doubles discharge rate doubles A low x means that the discharge rate does not vary greatly when pressure varies Most high quality drip tape products have x values in the range of 0 4 to 0 7 Some lower quality products have x values greater t
140. served by center pivots Center pivot irrigation cannot provide the same per acre yield or complete utilization of rectangular fields that is possible drip irrigation In fields where there is already a significant investment in center pivot hardware yield can be increased by using drip tape to irrigate the corners EXAMPLE vl Feed Corn 7 Kansas USA 1320 Z Z e v v v z Z Y 4 4 4 m n 4 9 lt 30 60 Operation Auxiliary Equipment CHOP avec qalawasa tatakunaqa ka com Primary filtration screen Location Kansas USA Secondary filtration none Field Size sas dama edi 80 acres Submains PVC Plants per acre 28 000 Mulch u e u e Lee none SEASON unpu aaa 2295406 a Spring f Planting method direct seeded Management 0peration Soil type sees ccc cies clay loam Irrigation frequency 3 days Maximum ET 0 4 in per day Irrigation duration 16 hours Water Source well Chemigation yes Groundcover 1 NONE Tertigation yes Crops rotated with soybeans Line flushing yes Time to maturity 120 days Filter back flushing yes Ave yield 200 bushels acre 17 5 m3 ha Duration of tape install
141. spacing meters If US units are used AR will be in inches per hour If metric units are used AR will be in mm per hour The application rate delivered by your system must be capable of replacing water lost to ET during the peak months of the season It is good practice to apply a safety factor when estimat ing your peak water requirements to account for system inefficiency as well as the possibility of equipment failure or extreme weather conditions EXAMPLE You plan to increase the output of your quarter section 160 acre 65 hectare corn field by replacing an existing center pivot with drip irrigation The corn is planted on 36 in 91 cm cen ters and you will use one RO DRIP 13 24 17 XL lateral for every two rows resulting in a 6 ft 1 8 m lateral spacing The peak ET for corn in your area is 8 5 in 216 mm in the month of July The capacity of your water supply is 1200 GPM 4500 LPM SOLUTION The peak daily ET requirement is 8 5 31 0 274 in per day 6 95 mm per day Using a 25 factor of safety to account for system inefficiency and possible interruptions in the water supply the system must be capable of an application rate of 0 274 x 1 25 0 343 in per day 8 71 mm per day or at least 0 014 in per hour 0 36 mm per hour if operated for 24 hours 160 acres x 43 560 160 x 43 560 L 1 161 600 feet 354 056m 6 feet 6 The system will be capable of delivering an application rate of 17 GPH per 100 17
142. ssive drag on the spool Avoid stretching the drip tape 5 Leave extra length at both ends of the laterals to allow for expansion and contraction and for connection to the manifold 6 After the first lateral is installed evaluate it for excess drag set on the spool Check the tension of the lateral by hand Periodically re evaluate drag throughout the installation Tape installation procedure surface Use the same basic procedure as with sub surface installation With surface installation however the means of securing the laterals are different Place a shovel full of dirt over each laterals every 10 15 ft 3 4 5 m to mini mize their movement by wind or thermal expansion and contraction as shown in figure 4 3 Manual Installation above Installation of Tape with Plastic Mulch For many crops the combination of drip RD4 3 irrigation and plastic mulch gives the greatest f f I degree of control over the root zone environ EE OR ee Figure 4 6 Mechanical Installation of Tape ment and results in higher yields and more efficient use of water and chemicals RO DRIP is available with Injection shanks can be mounted on tool bars along with plastic layers and bed shapers the wide variety of emitter Packaged systems are available from several vendors that lay plastic and inject tape fig 4 7 Some of these systems also shape beds spacings required for nurs ery and greenhouse appli Note Drip tape should be buried if it is used wit
143. stribution uniformity and higher irrigation efficiency in your field G 2 COEFFICIENT OF VARIATION AND EMITTER DISCHARGE EXPONENT Coefficient of variation If you randomly select several emitters from a section of drip tape apply the same water pressure to each and measure the discharge rate from each the Coefficient of Variation Co is a measure of how consistent the results will be If the emitters were manufactured with a high precision production process and good quality control the discharge rates of all of the emitters will be nearly identical and the Cv will be low On the other hand emitters made from a poor design an inconsistent manufacturing process or with little or no quality control will have wide variations in discharge rate and a high Co Co can be calculated by measuring the discharge rate from each emitter in a sample of drip tape usually long enough to provide 25 emitters then using the following formula S Cv q where S is the standard deviation of the discharge rates measured in the sample and q is the average discharge rate of the sample Most drip tape manufacturers publish the Cv of their products Several independent labs also test Cus and compare them among manufacturers A perfect manufacturing process is impossible so emitters with zero Cv all identical flow rates do not exist However since good Distribution Uniformity is impossible if emitter flow rates are not consistent you should
144. suited for deficit irrigation when necessary To determine how much water to apply during irrigation first calculate the amount needed by your crop for evapotranspiration and use this as a starting amount After irrigating you will be able to fine tune the schedule by examining the wetted pattern measuring soil moisture and making adjustments accordingly Determining Your Crop s Daily Requirements For most crops the soil in the root zone should be kept near field capacity at all times see PLANNING Water Requirements This means that irrigation should be frequent and the amount of water applied each time should be equal to the amount used by the plants since the last irrigation Therefore it is important to know the rate at which water is lost to Evapotranspiration ET The ET rate of a reference crop for you area is usually available from a local agricultural agency or in some areas through the Internet Portable weather stations are also available which can be more accurate since ET can vary from field to field Use the following formula to calculate the ET rate of the specific crop in your field ET Ke x ET where ETo is the reference crop evapotranspiration and Kc is a crop factor or crop coefficient that depends on the specific crop you are irrigating The value of the crop factor varies throughout the season as your crop matures You can estimate it by starting with the value shown in table 5 1 and multiplying it by the
145. t 8 5 ECw gt 3 0 TDS gt 2000 ECw lt 2 ECw lt 3 ECw lt 5 ECy lt 1 3 ECw lt 2 9 SAR gt 9 me l gt 9 me l gt 10 ppm gt 3 ppm gt 30 me l gt 8 5 1 High SARa accompanied with high ECw allows water penetration but is unacceptable for production of salt sensitive crops RO DRIP USERS GUIDE A 3 UNDERSTANDING YOUR WATER QUALITY REPORT Table A 3 Guidelines for Potential Emitter Plugging from Water Contaminants Emitter Plugging Hazard Type of Problem Moderate Severe Physical Suspended solids 50 100 ppm gt 100 ppm Chemical pH 7 0 8 0 Salt 500 2000 ppm Bicarbonate 100 ppm Manganese 0 1 1 5 ppm Total iron 1 0 2 1 5 ppm Hydrogen Sulfide 0 2 2 0 ppm Biological Bacterial population 2 500 gal 2 500 13 000 gal gt 13 000 gal 10 000 liter 10 000 50 000 liter gt 50 000 liter 1 When testing for iron and manganese acidify RO DRIP USERS GUIDE CROP PRODUCTION There are many variables involved in specifying a drip irrigation system design which can interact with each other in complex ways Coming up with the right combination of lateral placement drip tape wall thickness emitter spacing and flow rate is a complex process where experience plays an important role This appendix provides examples of how experienced growers have made design decisions for their specific crops Each page covers one crop and gives a description of general practices
146. t Pounds 2 66x106 CONCENTRATION Milligrams per Liter Parts per Million Millimho per Centimeter Multiply Multiply Decisiemens per Meter Milligrams per Liter Grams per Cubic Meter Millimho Milliequivalents per Liter Decisiemens per Meter Millimho per Centimeter Milligrams per Liter Parts per Million ppm Decisiemens per Meter Parts per Million Salt Grams per Cubic Meter Parts per Million ppm Parts per Million ppm Milligrams per Liter Parts per Million ppm Grams per Cubic Meter Parts per Million ppm Tons per Acre Foot 0 00136 Parts per Million ppm Grains per Gallon 0 0584 Parts per Million Salt Decisiemens per Meter 0 00156 Tons per Acre Foot Parts per Million ppm 135 Grains per Gallon To Convert Degrees Celcius C Parts per Million ppm ENGINEERING CONVERSION FACTORS 171 APPENDIX F TEMPERATURE 1 00 10 1 1 00 Degrees Fahrenheit F 1 8x C 32 Degrees Fahrenheit F Degrees Celcius C RO DRIP USERS GUIDE F 32 1 8 References Burt Charles P E Ph D amp Styles Stuart P E 1994 Drip and Microirrigation for Trees Vines and Row Crops The Irrigation Training amp researh Center San Luis Obispo CA Burt C 1995 Fertigation The Irrigation Training amp Research Center San Luis Obispo CA Solomon Kenneth Ph D P E 1999 Irrigation Equipment Performan
147. t plugging problems with acid Only use this procedure between crops 1 Flush all mains submains and laterals with clear water before injecting acid 2 Inject sufficient sulfuric phosphoric or muriatic acid to achieve a pH below 4 0 for a period of 30 60 minutes 3 Leave the acid solution in the system for 24 hours 4 Increase the system pressure to the maximum pres sure allowed for your drip tape for several minutes 5 Flush mains and submains first Close mains and submains and flush laterals 6 Run the system for one hour at elevated pressure 1 Repeat the procedure if plugging or contamination is severe flow channel Figure 5 3 RO DRIP s Expandable Flow Channel Pest Control Pests and small animal populations must be controlled Ants crickets wire worms other insects rodents coyotes and other small animals can cause severe damage to drip tape laterals Irrigating as soon as drip tape is buried can often reduce damage from wire worms by keep ing the soil moist enough that they do not seek out the tape Injecting certain pesticides can also help reduce insect damage consult a pest control advisor Damage from larger pests such as coyotes is more difficult to avoid Often a bucket of water placed in the field for animals will help keep them away from the drip tape Burying drip tape can also reduce damage from animals If pests are present in the field consult a pest control advisor before installing and using you
148. t with the drip lateral in the center The pairs of rows are 72 in 183 cm apart resulting in a between lateral spacing of 108 in 274 cm After a crop has been harvested and the ground prepared for the next crop the soil is very dry With newly planted stalks irrigate for 48 to 72 hours to wet the entire area between rows to a depth of 60 in 152 cm After the first long irrigation irrigate every other day Gradually increase the length of the irrigation cycle during the first 6 months After 6 months irrigate the cane for 24 hours every other day assuming no significant rainfall until maturity Upon maturity cease irrigation and begin harvesting when the sugar content is at its maximum In many areas including Hawaii phosphates are applied in granular form at planting time A typical granular fertilizer would be 10 30 10 A typical liquid nitrogen fertilizer would be Ammonium Nitrate 32 Fertilizer is generally applied through the system only during the first 10 months This is necessary to build sugar content NPK and trace elements can also be applied through the drip irrigation system Some varieties of sugar cane are salt tolerant and brackish water with up to 1500 ppm of total dissolved salts can be used for irrigation Sugar cane is also relatively drought resistant if you miss an irrigation cycle you can usually apply extra water during the next cycle without much adverse effect EXAMPLE f f Sugar Cane Venezuela
149. te control of organic matter see MANAGEMENT Maintenance Since organic matter is typically lighter than water it cannot be removed by a centrifugal sand separator Sand media filtration is the most effective method for removing most forms of organic matter The Roberts Difference Dissolved Minerals Dissolved minerals are found in most water sources and since they are dissolved would not be expected to cause emitter plugging However there are a number of factors that can cause manufactured to exacting these solids to precipitate or settle out These include changes in pH changes in temperature and reactions with commonly used fertilizers and chemicals The most common cause of precipi tation induced plugging is calcium carbonate lime precipitation Iron or manganese which produce a uniform wal may be dissolved in well water will precipitate when exposed to air or chlorine these precipitates are troublesome because they can lead to bacterial growth that can readily clog filters and emitters Sulfides can lead to similar bacterial growth and emitter plugging less breakage on installa Interaction of dissolved solids with your drip irrigation system can be highly complex and can change throughout the season In addition to their effects on the performance of your drip system dissolved ions can be both beneficial and detrimental to soil properties and plant health Perform a careful assessment of the dissolved solids in your water b
150. ter and add an appropriate amount about 2 tablespoons of the fertilizer mixture you intend to apply through the drip system 2 Mix thoroughly and let it sit overnight 3 If the mixture is cloudy the next day or if there is a precipitate in the jar do not use the fertilizer It will plug filters and or emitters Figure 5 4 Jar Test Specific Nutrients Nitrogen N Most nitrogen fertilizers are soluble in water and can be injected into drip systems with minimal problems Precipitation may occur however if they are mixed with other fertilizers For example injecting both calcium nitrate and ammonium sulfate into the same irrigation water will result in an insoluble gypsum precipitate that can readily plug emitters Phosphorus P In many cases phosphorus is applied before planting Phosphorous is especially important for seed emergence and healthy transplant growth and soluble phosphorus fertilizers can be expensive Growers often broadcast apply phosphorous before planting then supplement it later in the season through drip fertigation Most dry phosphorus fertilizers for general farm use are insoluble and cannot be injected into irrigation water Applying soluble phosphorus fertilizers through drip fertigation is challenging because they often react with other nutrients to form precipitates that can clog emitters In particular most phosphate fertilizers will form precipitates when injected into water containing calcium or magnes
151. til the soil under the moisture sensors is saturated If tensiometers are used this should produce a reading of 0 cb 2 4 RO DRIP USERS GUIDE PLANNING 4 Monitor the sensor readings daily When the readings level off usually after 2 3 days read and record the displayed values If using several sensors take the average of the 3 closest readings The result is the measured water content at field capacity If your sensor mea sures soil water tension the reading will generally be between 10 cb and 25 cb depending on soil type If your sensor measures moisture content the field capacity reading may range from 10 to 50 depending on soil type The optimum soil moisture level for most crops during vegetative growth stages is at or slightly below field capacity In general your system must be capable of replacing all water used by the crop since the last irrigation and must be used frequently enough to minimize depletion below field capacity Evapotranspiration Evapotranspiration ET is a measure of how much water is used by your crops for transpiration and how much is lost through evaporation from the plant and soil surface it is expressed in inches mm of water used per day or inches mm of water used per month ET measurements allow you to anticipate how the weather in your area will interact with your crop to determine water requirements ET values based on a reference crop for your region are usually available from local water
152. tion cycles 2 Compensate for irrigation inefficiency by dividing the resulting application amount by the irrigation efficiency IE Estimate IE as being equal to the distribution uniformity DU that you have designed for 3 Divide the amount of water to be applied by your system application rate AR see DESIGN Lateral Design The resulting irrigation duration given in hours is a starting estimate for your irrigation schedule After irrigating it will be necessary to make adjustments as described later in this section EXAMPLE Cantaloupes will be irrigated every other day using a drip irrigation system with the following specifications ET 0 19 in day Spacing between laterals 60 in 152 cm Emitter spacing 12 in 30 cm Drip tape flow rate 24 GPH per 100 ft 298 LPH per 100 m Distribution uniformity 90 Determine the required irrigation duration SOLUTION Since irrigation is performed every other day 19 x 2 38 in 9 7 mm of water must be replaced at each irrigation The distribution uniformity is 90 so 38 9 42 in 10 7 mm must be applied by the drip system at each irrigation Using the formula in DESIGN Lateral Design the application rate AR of the system is calculated as tape fl te GPH 100ft 24 GPH 100ft 24 ee eee ee a per 077 in per hr 1 96 mm per hr 62 x lateral spacing feet 62 x feet 62x5 AR The required duration T is the amount of water to be applied at each
153. tion needs of your crops under any field conditions This section will help you design a high efficiency drip irrigation system that meets the unique needs of each of your crops It starts by defining irrigation efficiency and explaining how it is affected by your choice of drip tape and other system components and how it can change with time After developing this background the section takes you through the steps of specifying components and designing the right system for your field Have a laboratory analysis of your irrigation water performed before beginning your system design Select a high quality drip tape This is a key decision in your drip system design To design drip laterals it is necessary to specify length of run emitter spacing placement depth position relative to plant rows and flow rate All of these decisions require in depth knowledge of your growing operation Your design must provide enough water to meet the needs of your crop under any conditions and must not require more than your water supply can deliver Proper filtration is crucial to prevent plugging of your drip system don t skimp on filtration components A good design includes pressure gauges flow meters and other instrumentation at key locations The Roberts Difference Precision manufactured RO DRIP products provide the quality and consistency needed for high uniformity and efficiency 3 1 DESIGN NOTE The guidelin
154. vantages Simple Recurring cost of drip tape Currently the most common j Low cost thin walled drip Cost of disposal use Single season tape can be used Environmental impact Can be retrieved with or with out mechanized equipment Re using drip tape may save Retrieval and re Proper maintenance is impor money installation can damage tant Reduced disposal require tape Requires a motorized ments retrieval head Retrieve and re use Potential for very long term Requires heavy gauge drip Proper maintenance is use tape critical Retrieval and re Between crop cultural prac installation is not tices require more care necessary during most sea Sons Multi season buried Reduced disposal require ments Disposal Retrieval operations are faster and simpler if the drip tape is disposed of Stretching and other damage is not important as long it does not interfere with the retrieval In most cases the drip tape must be disposed of in landfills which are placing stricter requirements on what they will accept If you are retrieving drip tape onto spools they should be compact and tightly wound If not loose drip tape should be tightly baled and tied Many landfills will not accept loose drip tape because of the damage it causes to their equipment Drip tape is designed to last many years without degrading or decomposing Disposal issues are likely to become more important as landfill space become
155. ve storage use and application of these potentially dangerous substances 2 6 growth See MANAGEMENT Germinating Seeds TOPOGRAPHY While topography clearly influences system design it can also be a motivating factor in the decision to implement a drip irrigation program Drip irrigation allows cultivation of uneven terrain that cannot be cultivated using furrow irrigation or certain types of sprinklers Drip irrigation is uniquely suited to growing on uneven terrain due to its flexibility in placement and its use of pressure to move water directly where it is needed Consider performing a survey to document your field s geometry and topography since this information will be useful in developing a complete system design PEST CONTROL Insects such as ants crickets and wire worms and animals such as rodents and coyotes can all cause damage to drip tape laterals Pest control should be initiated before placing drip tape laterals in the field and periodically thereafter as needed Where pests are a significant problem consider using thicker drip tape and or buried placement Consult a pest control advisor for guidance on controlling the specific pests found in your region CHEMIGATION FERTIGATION Chemigation Chemigation refers to the combination of irrigation and chemical water treatment into a sin gle process and is recommended to maintain a well functioning drip irrigation system Chemical treatment includes the use of che
156. velocity See the Accessories section of the Roberts Irrigation Catalog for more information on the end caps available from Roberts Irrigation Products Inc Valves and Pressure Regulators Drip systems rely on uniform emission rates from all emitters While pumps provide a basic level of pressure and flow volume many more minor adjustments are required to keep your system operating at optimum efficiency and safety The following types of valves may be required for your system Pressure regulating valve Pressure regulating valves keep downstream pressures constant in the presence of varying upstream pressures They do not affect water flow directly They can be of great value in limiting pressure differences across the field especially when installed at the beginning of each submain Pressure regulators must be sized according to the flow rates they will be subjected to and not according to submain size Be careful when installing pressure regulators since they can be damaged by water hammer Avoid low cost units that do not regulate downstream pressure but only maintain a pressure drop Pressure relief valve Use pressure relief valves when the pressure in your system has the potential to increase beyond a safe level Temporary high pressure conditions may occur with sudden opening or closing of valves or air vents or may occur due to water hammer The optimal location for pressure relief valves can be difficult to establish They generally sh
157. vide detailed guidelines on sizing pumps for irrigation applications OTHER COMPONENTS Fittings and Connectors Connecting laterals to submains Three basic methods used to connect drip tape laterals to submains are Direct connection using twist lock connectors Connection via transfer tubes and fittings Connection via transfer tubes without fittings Each of these methods is described in detail in INSTALLATION AND STARTUP Connecting Laterals to Submains Refer to the Accessories section of the Roberts Irrigation Product Catalog for information on the fittings and tubing that are available from Roberts Irrigation Products Inc Table 3 11 summarizes the advantages and disadvantages of each connection method Terminating laterals Laterals can be terminated into flushing manifolds see Mainlines and Submains in this section or they can be individually terminated with or without fittings The best method of terminating laterals is usually determined by the flushing requirements of your system The lowest cost method of terminating an individual lateral is to fold it over and use a short length of drip tape as a sleeve to slip over the fold This method is described in detail in INSTAL LATION AND STARTUP Threaded end cap fittings can be used to simplify flushing of laterals Automatic flushing end caps are also available although they should not be used in place of a regular flushing program because they do not allow sufficient flushing
158. water supply Tables E2 and E4 El LENGTH APPLICATION RATES AND FLOW RATES E 2 Table E 1 Length and Flow Rate Requirements US Units Drip Tape Flow Rate per 100 ft at 8 PSI Dist Length of Between DripTape 40GPH 24GPH 20GPH 17GPH 15 GPH Laterals pe 67cm soem 33GPM 28GPM 25GPM GPM Required per Acre in Table E 2 Length and Application Rates US Units Drip Tape Flow Rate per 100 ft at 8 PSI Between Drip Tape 15 GPH Si e 25 GPM Application Rate in per hour 8 PSI RO DRIP USERS GUIDE LENGTH APPLICATION RATES AND FLOW RATES Table E 3 Length and Flow Rate Requirements Metric Units Drip Tape Flow Rate per 100 m at 55 bar Dist Length of Between Drip Tape 497LPH 298LPH 2481PH 211LPH 186LPH Laterals per Acre a fs 8 3LPM 5 0LPM 4 1LPM 3 5LPM 3 1LPM M3 hr Required per Acre 12 500 11 110 10 000 9 090 8 333 7 692 7 143 6 667 6 250 5 882 5 556 5 263 5 000 4 762 4 546 4 348 4 167 Drip Tape Flow Rate per 100 m at 55 bar i Length of s Drip ape 497LPH 298LPH 2481PH 211LPH 186LPH Laterals 8 3 LPM 5 0 LPM 4 1 LPM 3 5 LPM 3 1 LPM Application Rate mm3 hr 55 bar 8 nso 625 35 312 261 230 100 10 000 5 00 2 98 2 50 pani 4 86 120 8 333 4 16 2 4
159. y your plants when they are injected into the root zone and what can be done to make existing nutrients more available Plant tissue tests can be performed throughout the season to determine the nutrient levels within your plants These tests are particularly useful because they directly indicate nutrient deficiencies that can be made up through fertigation Quick Tests for soil nutrient levels are now available and are becoming popular These tests can be used to monitor soil nutrient levels on farm and use the information to immediately make adjustments to your fertigation program Many laboratories can now perform soil sample tests tissue tests and or sap tests with a one day turnaround also allowing you to make necessary adjustments exactly when they are needed MANAGING SOIL SALINITY In arid regions such as the western US salinity management is important with all fruit and vegetable crops and is critical with strawberries Depending on water quality and soil type many other crops also require active salinity management especially during germination With good management the salinity of the soil solution can be 1 5 to 3 times the salinity of your irrigation water If salt is not managed properly the salinity of the soil extract can reach levels that are lethal to plants Symptoms of Salinity Problems Salt is added to the soil during each irrigation Adding fertilizers can further increase salinity Excess salt must be removed from the

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RO-DRIP® User Manual - TRICKL-EEZ