Design, Introduction, and Extension ofLow-Pressure Drip Irrigation in Myanmar

Brent Rowell1,3 and Mar Lar Soe2

ADDITIONAL INDEX WORDS. trickle, microirrigation, treadle pump, low cost, ultra-low pressure, Burma

SUMMARY. Drip irrigation is used extensively by both large and small commercialhorticultural crop growers in most developed countries where benefits include notonly highwater use efficiency, but also higher yields, improved product quality, andreduced incidence of foliar disease. Drip systems are still relatively new andexpensive in Southeast Asia, and it is primarily wealthier farmers who currentlyenjoy its benefits. There are also significant perceptual barriers to adoption as manyfarmers are accustomed to applying copious amounts of water to horticultural cropsand are unfamiliar with drip or their crops’ actual water requirements. As a non-governmental organization whose mission is to help boost small farm incomes,International Development Enterprises (IDE) began experimenting with low-pressure, low-cost gravity-fed drip systems inMyanmar (Burma) in 2006.While thebasic designwas similar tomicrotube drip systems of the 1960s, local improvementsincluded filters designed for low pressures, easy-to-use fittings, and inexpensivecollapsible header tanks. Our system was optimized for operation on small butcommercial-scale plots using pressures as low as 1 psi or only�1/10th of that usedfor conventional drip irrigation. Extension support materials included illustratedinstallation guides, systemdesign software, videos, testing/filtering of dissolved iron,and easy-to-use water requirement calculators. After hundreds of controlled andfarmers’ field tests, our locally manufactured drip sets were offered for sale by privatedealers throughout Myanmar in 2009. Incremental system improvements coupledwith a strong on-farm demonstration and farmer education program resulted in thesuccessful introduction and widespread adoption of drip irrigation in Myanmar.

Commercial horticultural cropgrowers in the United States,Europe,Australia,China,Korea,

Brazil, Mexico, South Africa, and theMiddle East enjoy the benefits of dripirrigation, which have been described innumerous research and extension publi-cations over the past 40 years. Well-known benefits include higher yields,improved product quality, and reducedincidence of foliar diseases (Locascio,2005). Other advantages over conven-tional irrigation include higher wateruse efficiency and application unifor-mity that is unaffected by wind andcauses less soil crusting. In some cases,

weed pressures are reduced, andfarmers can perform weeding andother field operations while irrigating.

Application of plant nutrients throughdrip systems (fertigation) enables pre-cise fertilizer placement and timing,resulting in better nutrient use effi-ciency. Drip has also been used suc-cessfully on saline soils and with salinegroundwater where other irrigationmethods are problematic (Hansonet al., 2009). Finally, drip has favorableinteractions with plastic mulches,which further boost yields and productquality. Less energy and labor aregenerally required; shifting to driphas been called the greatest strategicimprovement in water use efficiencyand energy savings over the past threedecades (National Research Council,2010).

Significant barriers limit the adop-tion of drip irrigation by small farmersin developing countries. These includehigh initial system costs (especially ifmost components are imported), theneed for relatively clean or filteredwater, and the tendency for emittersto clog with contaminants such asdissolved iron. Even more importantare perceptual barriers, which includethe apparent complexity of drip sys-tems and the almost instinctual firstreaction from farmers that drip will notsupply sufficient water for their crops.Some drip components, such as lateraltubing made from linear low-densitypolyethylene (LLDPE), are also occa-sionally damaged by rodents or otheranimals. Overcoming these barriers re-quires not only appropriate hardwaredesign, but also an equal emphasis ontechnical support, farmer education,and on-farm demonstration.

Having worked with drip irriga-tion for 12 years as an extension spe-cialist in the United States beforebeginning work with IDE inMyanmar(IDE,Denver, CO) in 2006, the seniorauthor understood firsthand drip’sbenefits after numerous demonstra-tions and trials with small commercial

UnitsTo convert U.S. to SI,multiply by U.S. unit SI unit

To convert SI to U.S.,multiply by

0.4047 acre(s) ha 2.47110.3048 ft m 3.28080.0929 ft2 m2 10.76393.7854 gal L 0.26422.54 inch(es) cm 0.3937

25.4 inch(es) mm 0.03940.4536 lb kg 2.20460.0254 mil mm 39.37011 ppm mg�L–1 16.8948 psi kPa 0.14500.9072 ton(s) Mg 1.1023

Features

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vegetable farmers in Kentucky (Rowell,1999). Given this background, we didnot spend a lot of time comparing dripwith conventional irrigation methodsas such trials were being conductedwithpositive results by many researchers inmany regions including Southeast Asia(Fandika et al., 2012; Palada andBhattarai, 2012; Palada et al., 2011).Our goal from the beginning was todevelop and promote a drip system,which was both easy to use and afford-able to small, commercial-scale fruit,flower, and vegetable growers. Sucha system must function well for a plotsize of at least 0.1 acre at extremelylow system pressures, usually obtainedfrom an elevated water tank. Anotherobjective was to help establish privatelocal manufacturing of all system com-ponents. Although the task of develop-ing a commercial low-pressure system(without benefit of motorized pumps)was daunting, knowing the large poten-tial benefits was amotivation enough tomake the considerable investments intime and money.

International Development En-terprises is a nonprofit, nongovern-mental organization that promotesaffordable irrigation technologies forsmallholders as its primary tool forraising incomes and reducing povertyusing design thinking and a businessdevelopment approach. IDE’s coun-try program in Myanmar becameProximity Designs (Yangon, Myan-mar) in 2011 after becoming finan-cially independent from IDEInternational. Proximity Designs’ so-cial enterprise activities focus on

creating and marketing affordableproducts and services for rural house-holds; both organizations use market-based approaches that treat poorfarmers as customers rather than aidrecipients. Most of Proximity Designs’products are locally made and soldat production cost, while research,design,marketing, and promotion costsare donor funded.

Myanmar, although currentlyisolated from its potential export mar-kets, produces large quantities of veg-etables to supply its population of�51 million people. The country hasdiverse agroclimatic zones rangingfrom tropical to temperate and growsan enormous variety of vegetablecrops including many that are consid-ered indigenous. The major commer-cial crops grown in 2007–08 werechili [Capsicum annuum (318,000acres)], tomato [Solanum lycopersi-cum (261,000 acres)], onion [Alliumcepa (175,000 acres)], and potato[Solanum tuberosum (90,000 acres)];these together with a wide variety ofother crops comprise a total vegetableproduction area of �1.8 million acres(Maung Maung Yi, 2009).

Motorized pumps were unafford-able to most small farmers in the firstdecade of the 21st century and theelectricity grid still does not extend tothe majority of Myanmar’s villages; itis therefore not surprising that in mostcases commercial horticultural cropswere irrigated by hand with largesprinkler cans (Fig. 1) or by furrow/flood irrigation. Irrigation with sprin-kler cans requires backbreaking andtime-consuming labor; our surveysrevealed that it was common for smallfarmers to carry 4–6 t of water on theirbacks daily to irrigate horticulturalcrops.

The following is a description ofthe evolution of a low-cost, low-pressure drip system and how thissystem has been demonstrated and pro-moted from 2006 to the present. Ourprimary goal was to develop and extenda practical and affordable low-pressuresystem in as short a time as possible; toaccomplish this, we used a combina-tion of rapid prototypes and quick fieldtests or screenings. Customers andend users helpedmake final judgmentsregarding suitability and performancethrough continuous on-farm demon-stration followed by both formal andinformal feedback surveys. While wehave tried to describe 8 years of this

work under broad headings of ‘‘systemdesign and development,’’ ‘‘farmers’field testing and demonstrations,’’and ‘‘local manufacturing, sales, andpromotion,’’ it should be understoodthat some of these activities tookplace simultaneously.

False starts and first attempts

Modern commercial drip systemsfrom Netafim Ltd. (Tel Aviv, Israel)were first introduced by company rep-resentatives and the Myanmar Agri-culture Service in one township inMandalay Division in 1994 and laterby an Israeli-local joint venture in 2006within a government-organized vege-table production zone in Yangon Di-vision. However, these efforts weresoon discontinued or abandoned be-cause of high management require-ments and expense in Mandalay, andas a result of iron clogging and otherproblems in Yangon Division.

When the senior author arrived inMyanmar in 2006 with the task ofintroducing drip irrigation, it was as-sumed (even by IDE) that this wouldbe as simple as demonstration andsales of IDE’s prepackaged ‘‘drip kits’’that had been imported from India.But, as we began to work with thesekits, it soon became apparent that theywere not suited to local horticulturalcrop production. The prepackaged kitsizes were often too small or too large,but a more serious problem was thatmain or submain-to-lateral connectorswere preinstalled at fixed spacingsthat did not match the most common

Fig. 1. Traditional sprinkler cans usedon horticultural crops throughoutMyanmar; a pair of these cans waters50 ft (15.24 m) of a 3-ft-wide (0.9 m)bed and weighs �70 lb (31.75 kg)when full.

This work was generously supported by grants fromthe Bill and Melinda Gates Foundation, the MulagoFoundation, and the Royal Norwegian Governmentto IDE and Proximity Designs.

We thank U Aye Tun of the Myanmar AgricultureService, Martin Pun of the FMI Estates, and U WinKyaing of the Shwe Dagon Pagoda Foundation forallowing us to use their grounds as our researchfields. We would also like to thank real irrigationengineers Jack and Andy Keller, Ryan Weber, andBob Yoder for technical help and advice. We alsoacknowledge the very hard work and support fromso many current and former IDE/Proximity col-leagues including David Klaus, Todd Murphy, TaieiHarimoto, Tun Tun Khine, U Win Maung, Ko ThanHtay Zaw, Ko Aung Naing, Ko Zaw Zaw,Htun ThiriSein, Myat Phyu The, Tin Aye Aung, Khun MyaMaung, Ko Soe Moe Lwin, Yin Yin Oo, JacquettaHayes, and Tim Mitzman.

1Department of Horticulture, N-318 AgriculturalScience North, University of Kentucky, Lexington,KY 40546

2East-West Seed International, No. (40/A), MyaSabal Road, Ma Yan Gone Township, Yangon,Myanmar

3Corresponding author. E-mail: browell@uky.edu.

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row-to-row spacings for horticulturalcrops inMyanmar. There were also nosubmain-to-lateral connectors avail-able that could be used with the in-expensive flexible pipe, which wasubiquitous in the country. In addition,importation of IDE drip kits fromIndia was slow, difficult, and expen-sive. For these reasons the IDE-Indianlateral tubing,microtube emitters, andscreen filters were removed from kitson hand and used in our own customon-farm installations and test plotsfrom 2006 to 2008, with incrementalsubstitution of our locally made com-ponents as they were developed.

IDE-India (New Delhi, India)had developed and popularized gardenand small commercial drip kits there inthe 1990s and early 2000s. The basicdesign was an adaptation of an oldermicrotube (spaghetti tube) emittersystem first introduced in Israel andtheUnited States in the 1960s (ChapinWatermatics, 1971). Although thistype of emitter system has long sincebeen abandoned for field use in de-veloped countries in favor of moreconvenient (built-in) labyrinth or tur-bulent flow path emitters, microtubeemitters are still used in greenhouses inthe United States and elsewhere.

Significant improvements to themicrotube system had been made byJ. Keller, J.N. Ray, and others in Indiawhere use of these systems becamewidespread through IDE’s market-ing and promotion efforts (Keller,2002; Keller et al., 2001). The lateDr. Keller (former Chief ExecutiveOfficer, Keller-Bliesner Engineering,Logan, UT, and Professor Emeritus,Utah StateUniversity, Logan,UT)wasa global authority on irrigation engi-neering and spent a large part of hisprofessional career helping develop af-fordable systems for low-income farmersin India and throughout the developingworld. Most low-pressure drip systemsfor developing countries, includingMyanmar’s, are based on his pioneeringwork.

System design anddevelopmentLateral/emitter screenings

Somewhat skeptical of the micro-tube system, we began a series of quicktests of various emitter types/lateralsin a commercial vegetable grower’sfield at Bauk Htaw, an area of leafygreens production within Yangon

(Rangoon) city limits in late 2006(Fig. 2). These tests were intended toeliminate the worst performers usingvery low pressures from elevated grav-ity tanks (height to the bottom of thetanks was 3.5 ft, equivalent to 1.5 psi).Relatively dirty surface water waspassed through simple 1-inch, 100-mesh screen filters mounted betweeneach tank and its drip laterals. Leaflettuce (Lactuca sativa) was grown(Dec. 2006 to Jan. 2007) followedby leaf mustard [Brassica juncea (Feb.to Mar. 2007)]. Both crops weregrown in raised beds 50 ft long and3 ft wide as is normal farm practicefor leafy vegetables in Myanmar. Cropmanagement (other than irrigation)and marketing were the responsibilityof the local grower.

Two 50-ft lengths of each lat-eral/emitter type were used on eachbed. Six lateral/emitter systems weretested including three with moderateto high flow rates: KB brand micro-tube system (IDE-India), Nepal’s(IDE-Nepal, Kathmandu,Nepal) ‘‘baf-fle’’ emitter system, and a labyrinthflow path emitter product called Adri-lite� (Adritec, Aman, Jordon). In theold IDE-India and current Myanmarsystems, 8- to 10-inch-longmicrotubesare pushed into thin-walled lateral tub-ing wherever an emitter is desired.Microtube i.d. was 1 to 1.1 mm, with

high flow rates of �0.5 gal/h peremitter. Manufacturers for IDE-Indialater eliminated microtubes in favorof simple prepunched holes at fixedspacings.

The three low-to-moderate flowrate systems tested with labyrinth flowpath emitters were T-Tape� (RivulisPlastro, Kibbutz Gvat, Israel), ChapinWatermatics drip tape [Chapin (JainIrrigation, Watertown, NY)], andDas drip tape [Das (Das Agroplastics,Pune, India)]. These were also com-pared with a control plot, which waswatered by traditional practice withtwo 4-gal sprinkling cans (Fig. 1).All plots were watered daily usingequal amounts of water. Yield andproduct quality were measured byharvesting all plants in the bedwithin a 10-ft-long subplot. Emitterflow rates from the different systemswere measured indirectly by record-ing the amount of water dischargedhourly from each of the 55-gal plas-tic drums providing water to the dripsystems (Fig. 2).

Open-pollinated leaf lettuce andleafmustardwere grown at equidistantspacings in seven rows/bed. Emitterflow uniformity, while not measureddirectly, was observed by rating plantuniformity and vigor within the bedsunder the different drip systems. Anyproblems with flow or emitter

Fig. 2. Low-pressure screening of drip laterals and emitter systems on beds of leaflettuce at Bauk Htaw in Yangon, Myanmar in Dec. 2006.

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clogging were also noted. Althoughemitters were soon hidden from viewunder dense plant canopies, it was easyto know when clogging occurred bythe lack of flow over time from thegravity tanks and resultant poor plantgrowth.

LABYRINTH VS. MICROTUBE. Inthese tests, the lower flow rate driplaterals generally performed betterthan high flow rate products (datanot shown), although no firm conclu-sions were possible without furtherreplication. It was obvious that low-to-moderate flow rates from labyrinthflow path emitter products (T-Tape�,Das, Chapin) resulted in higher yieldsandbetter uniformity of densely plantedleafy greens than from IDE-India’s KBbrand microtube or IDE Nepal’s ‘‘baf-fle’’ systems with their very high flowrates. Some of the drip systems resultedin yields equal to or slightly higher thansprinkler can watering for leaf lettuce,but not for leaf mustard. However,direct comparisons with sprinkler canwatering were beyond the scope of thistest.

The reasonwhy low flow rate driplaterals performed better became ob-vious as the season progressed. Bothleaf lettuce and leaf mustard formedsolid plant canopies, which completelycovered the bed surface, and withinthese canopies it was easy to see thatplants in rows farthest from the highflow rate KB (microtube) and ‘‘baffle’’emitters were not receiving sufficientwater. We believe this to have oc-curred because of the wide beds andhigh flow rates. Although soils at thislocation were medium textured, localhand preparation of beds resulted ina somewhat rough and cloddy soilsurface permitting little capillary watermovement in the first few inches ofsoil. Water behaves differently in soilat high and low flow rates; the soilmatrix becomes saturated and gravityis the dominant force at high flow ratescausing more downward movementof the water column, while watermoves more by capillary actionthrough small pore spaces in the soilat lower flow rates, resulting in water,which is pulled in all directions and theformation of a larger wetted area. Oncoarse-textured soils, the wetted radiusincreases as drip discharge rates de-crease (Cote et al., 2003),whichwouldresult in more uniform plant growthacross wide beds with lower flow rateemitters.

Although we do not considerdense plantings of leafy greens in widebeds particularly suitable for drip be-cause of the extra cost of multiplelaterals, they were quick and easy in-dicators of emitter/drip system perfor-mance. However, if we had used onlythese preliminary findings, we mighthave selected a labyrinth flow pathemitter system as the best choice forMyanmar farmers. As it turned out,there were other selection criteria in-cluding resistance to clogging, andmoreimportantly, ease of manufacturing.

Figure 3A and B show waterdischarge rates for the six drip

lateral/emitter systems with leaf let-tuce on 21 and 27 Dec. 2006. They-axis indicates the number of gal-lons remaining in the tanks, while thex-axis is the number of hours afterbeginning irrigation that day; steeperlines indicate faster discharge andhigher flow rates. The data from 21Dec. in Fig. 3A show more or lessnormal flow rates at very low pressuresfrom all systems. However, dischargerates for 27 Dec. shows that someclogging has occurred in three of thelabyrinth flow path emitter laterals in-cluding T-Tape�, Chapin, and, toa lesser degree,Das (Fig. 3B). T-Tape�

Fig. 3. Water remaining in header tanks 0.5 to 7 h after starting drip irrigation onleaf lettuce from six different lateral/emitter systems: 1) Baffle emitter laterals(IDE-Nepal, Kathmandu, Nepal), 2) Das tape (Das Agroplastics, Pune, India),3) T-Tape� (Rivulis Plastro, Kibbutz Gvat, Israel), 4) KB drip microtube system(IDE-India, New Delhi, India), 5) Chapin drip tape (Jain Irrigation, Watertown,NY), and 6) Adrilite� drip laterals (Adritec, Aman, Jordon). Tested in Yangon,Myanmar on 21 Dec. (A) and 27 Dec. (B) 2006; 1 gal = 3.7854 L.

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appears to have been partially blockedwhen irrigation began and completelyblocked 4.5 h later. Although a thor-oughflushing the followingday resultedin better flow from these laterals, theproblem persisted.

We continued to measure hourlyflow from all treatments for 1 weekafter harvesting leaf mustard on 10Mar. By 15Mar., 90% of the T-Tape�

emitters were clogged and by 16Mar.,60% of Chapin emitters were partiallyor completely clogged together with90% of Das lateral emitters. Attemptsto clean and reuse these laterals ona third crop were unsuccessful. Itshould be understood that we purpose-fully tested these systems under difficultconditions for drip; water at the site wasdirty surface water from a nearby citydrainage canal. Knowing that mostlocal farmers could not afford expensivesand or disc filters, we used only simple100-mesh screen filters in these tests.Under these conditions of inadequatefiltration, all labyrinth/turbulent flowemitters (with the possible exception ofAdrilite�) became clogged after onlytwo short-season crops over a periodof �70 d.

Although Adrilite� laterals ap-peared to be more clog resistant thanother labyrinth flowpath emitter prod-ucts in our tests, this product hascomplex injection-molded emittersthat are installed during the extrusionprocess—a manufacturing process im-possible to duplicate in Myanmar atthe time. While IDE-Nepal’s baffleemitter system was also resistant toclogging, we did not like its fixed(prepunched) emitter spacing and verysmall lateral diameters that could limitits use in larger commercial plantings.For these reasons, we selected themicrotube emitter system for furthertesting as it appeared to be the mostrobust in terms of clog resistance, wasflexible in terms of emitter spacing, andwould likely be the easiest to manufac-ture. We also decided to do furtherfarmers’ field testing of Das laterals thefollowing dry season on farms withrelatively clean well water.

Whole system testingSignificant limitations of our cus-

tomdrip installations usingmostly IDE-India components became apparentafter extensive countrywide farmers’field testing during the 2007–08 and2008–09 dry seasons. Customer satis-faction was disappointing with frequent

user complaints of ‘‘not enough water’’from emitters farthest from the watertanks. In addition, nearly nothing wasknown regarding the size limits orwaterapplication uniformity of these systemsfor given tank heights/operating pres-sures, main line diameters, and fieldarrangements of laterals.

Although some information onlow-pressure, gravity-fed drip systemperformance was available from IDE-India, most of it was not applicable tolocal pipe sizes and drip componentswe used in Myanmar after 2008. Wealso did not know the best possiblearrangement of main, submains, andlaterals to achieve maximum applica-tion uniformity at very low operatingpressures. To answer these and otherquestions, we conducted over 100 fieldtests on a level 1-acre vacant plot inYangon from Mar. to June 2009.

In nearly all of these tests, the‘‘bottom line’’ dependent variablewas the coefficient of uniformity(CU) proposed by J. Keller (2002 andpersonal communication) as the stan-dard measure of application unifor-mity for smallholder drip systems. TheCU is derived from the coefficient ofvariation (CV) of catch can observa-tions. The catch can CV is a measure ofthe variability of the amounts of watercollected in catch cans placed underdrip emitters at different locations

within a test field (Fig. 4), and is easilycalculated using a hand calculator orspreadsheet as follows:

CV =SD

q3100

where SD is the standard deviation of thecatch can amounts of the populationand q the overall average of all catch canobservations. The CU is simply 100 – CV,and therefore a measure of water appli-cation uniformity. We used a CU of 80%as the minimum acceptable value asproposed for smallholder drip andsprinkler irrigation systems in develop-ing countries (Keller, 2002).

Three groups of six catch canseach (18 total) were buried so thatwater from individual microtubesflowed easily into the containers. Thefirst group of six cans was placed nearthe end of the first lateral closest to thewater tank or main line, the second inthe center of a lateral at the center ofthe plot, while the third was near theend of the last lateral (Fig. 4). Waterwas collected in the cans for 3 min andmeasured, after which the CU was cal-culated and the test repeated.

Independent variables examinedin this first series of tests includedwater tank height, main line diameter,splitting of lateral lines with a centersubmain, placement of the main line

Fig. 4. Catch cans and intravenous tube manometers used in drip system waterapplication uniformity testing in Yangon, Myanmar in 2009.

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(side or center of field), use of a ‘‘T’’connector to join the main line tosubmains, and so on. In all cases, wedetermined the maximum numberof emitters (and length of laterals)that could be used and still maintaina CU of 80%. To do this, we firstselected what we considered a reason-able number of emitters/laterals andthen increased or decreased this num-ber after each test until the minimumCU was reached.

Water tank to ‘‘Water Basket’’Elevated water tanks used for

these tests and for most on-farm in-stallations after 2007 were prototypesof what came to be known as IDE orProximity Designs ‘‘Water Baskets.’’The concept and initial design of theWater Basket came fromcollaborationswith Stanford University’s (Stanford,CA) ‘‘Design for ExtremeAffordability’’graduate classes in 2006 and 2007.The first version consisted of inexpen-sive plastic tarp material folded andriveted to form cubical 200-gal water-tight containers. These Water Baskets,used in our early drip system tests anddemonstrations, were mounted atopsturdy 5- to8-ft-tall bambooorwoodenstands. However, these earlier versionswere not entirely self-supporting, and

had to be enclosed within bamboo orwooden sidewalls (Fig. 5, left).

Only a summary of the mostrelevant findings is reported here. Af-ter comparing 4-, 6-, and 10-ft tankheights, we chose to use 6 ft (height tobottom of the tank) in conjunctionwith locally available 11/4-inch (1.2-inch i.d.) flexible pipe for main and/orsubmains.One-inch (0.9- to1-inch i.d.)pipe reduced flow and system perfor-mance considerably while 1½-inch flex-ible pipe did not offer sufficientadvantages to justify its high cost forsmall drip systems. Performance maynot have improved with the local 1½-inch pipe in part because of the smalldiameter Water Basket outlet used inthese tests.

Several field arrangements ofmain, submains, and laterals were com-pared for best performance under lowpressures; results were simplified as‘‘good,’’ ‘‘better,’’ and ‘‘best’’ illustra-tions (Fig. 6),which appeared in the firstedition of our installation and users’guide (Rowell and Soe, 2009). Theseresults also led to the design and man-ufacture of new components for 2009including two sizes of plastic ‘‘T’’ fittingsused to join mains to submains. Thetests also revealed significant gains inpressure and flow from removing the

ordinary 1-inch screen filter as wasreported by some of our customers.We decided that the advantages of usinga simple filter outweighed potentialgains in pressure and system size with-out one; all subsequent guidelines formaximum zone sizes and number ofemitters published in our installationguides were obtained from tests thatincluded screen filters. The effect offilter design on flow rate at very lowpressures was studied more in depth inthe 2010 tests described below.

Component testingAlthough the 2009 tests resulted

in a better functioning system thatcould be optimized for uniformityusing different arrangements of mainsand submains, further studies wererequired. In the interim, our 2009results were shared with J. Keller whoobserved that we were losing much ofour system pressure at some point orpoints between the elevated tank andthe junction of the main line to thefirst lateral. A series of 80 field tests wassubsequently conducted in early 2010to try and pinpoint the source(s) ofthese losses and to redesign the systemto minimize them.

Unlike previous tests, we did notset up a full drip system but used onlya 6 ft-highWater Basket and its fittingstogether with a 100-ft length of 11/4-inch local flexible pipe with a ball valveon the end to simulate total systemflow. A single 45-ft lateral with sixmicrotubes at its far end was connect-ed to the main line at a distance of 9 ftfrom the water tank. Two microtubeswere inserted in the main line betweenthe Water Basket and the first lateral�1 ft from the lateral-to-main lineconnection.

System pressures were measuredusing the microtubes described aboveconnected to simplemanometersmadefrom 6- to 10-ft lengths of transparenttubing sold for medical use (i.e., in-travenous or ‘‘IV’’ tubing). The tubingwas mounted on vertical stands madefrom steel angle iron or bamboo withcloth measuring tape attached behindthe tubing (Fig. 4). Pressure wasmeasured as the height of the watercolumn in the tubing; measurementswere also taken from manometersattached to two of the microtubes atthe end of the single lateral.

All 2010 tests were conductedusing two system flow rates corre-sponding to small (average 500 gal/h

Fig. 5. Old elevated International Development Enterprises-Myanmar (Yangon,Myanmar) foot-operated treadle pump and 200-gal (757.1 L) Water Basketsupported by bamboo sidewalls in Myanmar in 2008 (left). Proximity Designs’(Yangon,Myanmar) ‘‘Sin Pauq’’ (baby elephant) elevated pumpwith treadles on theground together with Proximity Designs’ new self-supporting Water Basket inMyanmar in 2012 (right).

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or equivalent to �1000 microtubeemitters at 0.5 gal/h per emitter) andmedium-sized (average 970 gal/hor �1940 microtubes) drip systems.Flow rates were determined beforeeach test by direct measurement atthe far end of the main line. Highflow was simulated with an openvalve whereas the lower flow ratewas simulated by partially closingthe valve. Twenty-seven existingand alternative components and fit-tings of the Water Basket and dripset were tested for their effects onsystem pressures; only the most im-portant results are summarized here.

Rigid, nominal ‘‘1-inch’’ polyvinylchloride (PVC) pipe (11/4-inch i.d.)resulted in lower head losses thanlocally made flexible 11/4-inch pipe(1.2-inch i.d.), at least for the first 2 ftbelow the Water Basket where the

pipe joined the filter. To simplify in-stallations, we chose to use this rigid1-inch PVC for the entire lengthof pipe required between the WaterBasket and ground at which pointlocal 11/4-inch flexible pipe could beused as the main line without signif-icant additional pressure losses. Theold outlet used on Water Baskets wasalso found to restrict flow and wasenlarged to an i.d. of 1.34 inch.

‘‘LOW-LOSS’’ FILTER.Many of the2010 tests were aimed at reducinglarge pressure losses from our standard1-inch screen filter, which was thesame design used by IDE-India andin other small drip systems. Losseswere the same with this type of filterregardless of whether it was manufac-tured in India or Myanmar andamounted to nearly half the total sys-tem pressure at low flow rates [‘‘IDE

screen 80’’ (Fig. 7)]. This should notbe surprising as these filters weredesigned for use with higher systempressures than are obtained from grav-ity systems using only 3- to 6-ft highheader tanks (1.3–2.6 psi). To resolvethis problem, we tested three filter de-signs mounted at the outlet inside theWater Basket and four new prototypescreen filters mounted in the usualposition between theWater Basket out-let and the ground.

A summary of results comparingpressure losses from some of thefilters and prototypes tested is shownin Fig. 7. Although all filters mountedinside the Water Basket performedwell without significant losses, wedecided not to use this type as theywere difficult to remove for clean-ing. The straight in-line external filterprototype shown in Fig. 8A lookedpromising with relatively low pressurelosses (23% of total head) at low flowrates more typical of our drip systemsize. However, this design requiredthat the entire filter body be removedfrom the line to clean the screenelement. The prototype in Fig. 8B wasdesigned to overcome this problem andperformed just as well, reducing totalhead losses from 46% with the ordinaryfilter to only 18% [equivalent of nofilter in our tests (Fig. 7)] while allow-ing easy access to the filter element forcleaning.

On the basis of these findings,our design and manufacturing teamsdeveloped the final form of the in-jection molded filter body shown inFig. 8C and D, which was used in ourdrip sets from 2010 to 2013. Whiledesigned for tight friction fits withordinary rigid 11/4-inch PVC pipeand small drip systems, local farmersalso used it with flexible pipe sub-mains at higher pressures in largersystems using motorized pumps. Af-ter changing to this filter, we receivedno further complaints of pressurelosses and almost never saw drip sys-tems in the field with filters removed.The net result from these changes inthe filter and other components wasthat with the same low system pres-sure we could now effectively irrigateover twice the area as the systemused before the 2010–11 dry season.This was equivalent to two full dripsets (1200 emitters) or �7800 ft2 ofhorticultural crops with a minimumCU of 80% and 6 ft Water Basketheight.

Fig. 6. Simplified low-pressure drip system layouts for plot sizes up to 0.2 acre [0.08ha (maximum 1500 microtube emitters)] and 1/3 acre [0.13 ha (maximum 1600emitters)] using a 3 ft (0.91 m) water tank outlet height (Rowell and Soe, 2012).

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Low-pressure system designsoftware

Performance of low-pressure,gravity-fed drip is inherently highlysensitive to small pressure variations.Given the large number of compo-nents and fittings affecting perfor-mance, and having gone through thelaborious process of field testing ofeach part to optimize the system, webelieved a computer software designtool would be extremely useful forimproving current and testing newconfigurations and designs. Softwarewould also enable us to determine thebest system configurations for fieldslarger than the size of two of our dripsets. While a good Excel� (MicrosoftCorp., Redmond, WA) spreadsheethad been developed for IDE by A.Keller (Keller-Bliesner Engineering),it was limited to testing only a fewindependent variables and was notuser-friendly enough for use by ourfield staff.

Our goal was to develop an easy-to-use program both for specialistsmaking component design changesand for drip technicians and field staffdesigning custom systems for farmers.While the2010tests resulted in significantimprovements in low-pressure systemperformance, we did not have time todetermine exactly what these improve-ments meant in terms of system size,maximum number of emitters (i.e., zonesize), and field configurations like thoseshown in Fig. 6. We decided to invest insoftware development to answer theseand other questions rather than beginanother time-consuming series of fieldtests.

Irrigation engineer R. Weber(IDE International) was hired in early2011 to develop a low-pressure hy-draulic model based on field tests inMyanmar. An experimental drip sys-tem was installed within a 2-acre plotof turfgrass in Yangon on the west sideof the YangonRiver. In addition to theusual IV-tube manometers, in-linepressure sensors with data loggerswere used to monitor small changesin system pressure. Measurements alsoincluded tests of water applicationuniformity of microtube emitters.

R. Weber and T.T. Khine (un-published data) conducted a series offield trials in early 2011 that resultedin a computer model for low-pressuredrip systems. The model is being usedto develop user-friendly software forpersonal computers and other

Fig. 7. Relative pressure losses from no filter, ordinary International DevelopmentEnterprises (IDE) screen filter (IDE screen 80), straight pipe filter prototypes(Straight 60 and 80), and new filter prototype (D-80) at low and moderate systemflow rates in Yangon, Myanmar, in 2010 (see also Fig. 8). IDE screen 80 was anordinary 80-mesh screen filter manufactured by IDE-Myanmar/Proximity Designs(Yangon, Myanmar) from 2007 to 2009. Straight 60 and 80 filters had 60- and80-mesh screens, respectively; the D-80 prototype used an 80-mesh screen.

Fig. 8. Screen filter prototypes for low-pressure drip: straight (A), D-80 (B) with80-mesh screen and the final product ‘‘Low-Loss’’ filter (C and D). Low-Loss filterswere manufactured by Proximity Designs (Yangon, Myanmar) from 2010 to 2013.

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portable electronic devices. Weber’smodel uses basic hydraulic principalsalong withmeasured characteristics ofindividual drip system components toshow the effects of component designchanges, main, submain, and lateraldiameters, various field layouts, andeffects of inlet pressure on overall sys-tem performance. It was used todetermine the maximum numberof emitters/laterals for different systemconfigurations using new drip compo-nents and fittings designed for the2011–12 and 2012–13 dry seasons.The results were published using thesimple good, better, best illustra-tions in our revised installation guides(Fig. 6).

In addition to recording obser-vations for software development,R. Weber and T.T. Khine (unpub-lished data) tested samples of thin-walled 2½-inch-diameter layflat for itssuitability for use asmain and submainsin our drip system. This tubing wasevaluated in conjunction with ourexisting drip system components andresulted in further reductions in pres-sure losses, not only because of itslarger diameter but also due to itsmuch smoother inner wall surfacecomparedwith local flexible pipe. Bothfactors dramatically reduced lossesfrom friction within the pipe, especiallyat higher flow rates in larger systems.

From low- to ultra-low pressureFurther modeling and field test-

ing in early 2012 revealed that 2-inch-diameter layflat made from a mixtureof LLDPE and low-density polyethyl-ene (LDPE)would be ideal in terms ofreducing pressure losses, low cost, andmaximum gravity-fed system size. Us-ing a 2-inch layflat main line, it wasconfirmed in the field that a tankheight of only 2 ft (from tank outletto ground) or 0.9–1.5 psi was suffi-cient for uniform water application(CU ‡ 80%) through a drip system ofthe size of the 2011–12 drip set(�4000 ft2). A height of only 4 ft or1.7–2.8 psi would uniformly irrigatea plot twice the size of that season’s setor nearly 0.2 acre with 4-ft row-to-rowspacing used formany commercial hor-ticultural crops in Myanmar.

TWO-INCH SYSTEM. Two-inchlayflat (1.9-inch i.d.) was manufacturedso as to fit tightly over short lengths of1½-inch-diameter local PVC pipe foreasy extension or repairs of main andsubmains. We made the new tubing

with a 12-mil wall thickness to reducecosts while having a reasonable life ex-pectancy of three to four seasons. Thenew tubing was manufactured duringthe Summer of 2012 by a small work-shop which had been making our driplateral tubing using similar LLDPE/LDPE recipes for both products.

The new layflat was not only halfthe cost of the local flexible pipe wehad been using, but was extremelycompact and could now be includedas part of a complete small plot dripset (Fig. 9A). But changing to thin-walled layflat and an all 2-inch systemrequired redesign of almost all othercomponents including take-off fittingsfor connecting laterals to mains/sub-mains, filter, and the Water Basketoutlet; these design changesweremadeover the next 2 years.

NEW CONNECTIONS. The firstcomponent slated for redesign in2012 was the take-off connector usedto join laterals to mains or submains.Design specifications included not onlya stepped connection to accommodatemanufacturing variations in lateral tub-ing, but also a nonleaking seal for thin-walled layflat and locking rings for usewith motorized pumps at higher pres-sures. While six different off-the-shelfconnectors from Thailand and theUnited States were tested with the newlayflat, none were designed for thin-walled tubing and none could be usedwithout excess leakage. All were testedat pressures up to 15 psi for suitability

for use with both gravity and engine-pressurized systems.We eventuallymadea successful prototype using a wide-screw-type ring, which provided moresealing surface area and with a smallergap between the insertion barb and thestepped connector body; a simple lockring was also provided to better securelaterals used with motorized pumpingsystems.These injectionmoldedconnec-tors were locally manufactured for inclu-sionwith the 2-inch layflat in drip sets forthe 2012–13 dry season (Fig. 9G).

NEW WATER BASKET AND FILTER.Proximity’s design team had in themeantime developed a new and ro-bust free-standing 200-gal WaterBasket (Fig. 5, right) with an outletfor 11/4-inch PVC pipe, which wasused to accommodate the new Low-Loss screen filter used from 2010 to2013. While we intended to transi-tion to an all 2-inch system, there wasno time to redesign the filter to fit 2-inch layflat prior the 2012–13 dry sea-son. The design team later developeda new, inexpensive in-line ‘‘sock’’ filter(Fig. 9D) for 2013–14 based on anearly prototype tested by Weber in2011. The team also developed rigidinjection-molded elbows and a newWater Basket outlet for 2013–14;this entirely 2-inch system (Fig. 9;Table 1) is currently available fromProximityDesigns inMyanmar (2015).While a minimum Water Basket heightof 3 ft is recommended for a single dripset, this ultra-low-pressure system will

Fig. 9. Proximity Designs’ (Yangon, Myanmar) ultra-low-pressure drip set for2014–15: (A) 2-inch layflat for main/submain, (B) rolls of 5/8-inch lateral tubing,(C) rigid plastic elbows, (D) sock type screen filter for easy installationwithin 2-inchlayflat, (E) couplers for lateral repairs and extensions, (F) punch for installingconnectors in 2-inch layflat, (G) take-off connectors for joining laterals to 2-inchlayflat, (H) 1½-inch ball valve and PVC pipe, (I) microtube emitters. Water Basket(J) is sold separately; all of the above components are made in Myanmar (see alsoTable 1); 1 inch = 2.54 cm.

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also perform well at tank heights of aslow as 2 ft or equivalent to �1 psi.

Farmers’ field testing anddemonstrationsFirst introductions, 2007–08

Ten small, preliminary farmers’field tests were established in Jan.–Mar. 2007. In most cases our plotsconsisted of 300–600 ft of drip lateralsapplied to a few rows within a farmer’sexisting commercial planting, whichwas watered by sprinkler cans, furrow,or elevated tank and hose before dripinstallation. Old 55-gal steel oil drumson 4- to 6-ft-high stands were used asheader tanks to pressurize these systems.

Ordinary 1-inch, 100-mesh screenfilters from IDE-India were used to-gether with Tape-loc� (Rivulis Plastro)main-to-lateral take-off connectors. In-ternal diameters of those connectorswere only 0.16 inch, which limitedoverall system performance in these tri-als. The main line was 1-inch-diameterflexible pipe (recycled PVC) availablethroughout Myanmar. In some casesIDE’s foot-operated treadle pumps

were mounted on stands above thedrums for easier filling. This requiredthe user to operate the pump fromabove the tank (Fig. 5, left) or usetreadles on the ground linked to thepump by ropes or cables. This prac-tice of filling elevated tanks withtreadle pumps existed in some partsof Myanmar even before we beganintroducingdrip. In a few cases, farmersfilled tanks by hand from nearby wells.Either the microtube emitter systemfrom IDE-India or Das turbulent flowemitter laterals was used in these tests.Das laterals were used only at siteswhere wells were the water source.

Results of these first farmers’ fieldtrials were mixed, and limitations ofthe systems tested quickly becameapparent. Only about half the farmerswere satisfied with system perfor-mance and some were quick to stopusing it and return to watering withsprinkler cans. Those who had to fillelevated tanks by hand using sprinklercans or other containers could not seeany obvious advantage over wateringwith the cans directly. We concludedthat few farmers would adopt drip for

commercial plantings if required to fillelevated tanks by hand. Other farmersobserved that water application wasnot uniform, especially when lateralswere over 70 ft long; still others de-scribed the common fear that dripcould not possibly supply enough wa-ter to their plants.

Other serious challenges observedduring this season included the old oildrums themselves, which were expen-sive, relatively small, difficult to trans-port, and difficult to fit with a properoutlet. Plastic drumswere not availablein rural areas and were even moreexpensive than steel drums. Althoughsteel or plastic 55-gal drums werereportedly used with small gravity-fed drip systems promoted byIDE-India and other organizationsin so-called ‘‘drum kits’’ (Ngigi,2008; Smeal et al., 2008), we con-cluded that two of the most criticalelements of simple and inexpensivelow-pressure drip systems would becheap and easily elevated watertanks in combination with treadlepumps or other simple means offilling these tanks.

Table 1. Components of Proximity Designs’ (Yangon,Myanmar) ultra-low-pressure drip system for the 2014–15 dry seasonin Myanmar (see also Fig. 9).

Item Unitsz Quantity Descriptionz

Drip lateral tubing 300-ft roll 3 5/8-inch-diameter LLDPE/LDPEy tubing (8 mil wall thickness),no emitters

Microtube emitters Bundles of 150 4 10-inch-long microtubes with 1–1.1 mm i.d.Main/submain pipe 100-ft roll 1 2-inch-diameter (1.9-inch i.d.) LLDPE/LDPE layflat, 12 mil wall

thicknessTake-off connectors Connector with

locking ring30 Injection molded with large (10 mm) i.d.; variable (stepped) o.d.

accommodates variations in lateral tubing diameter. Lockingrings secure laterals for motorized pumps, higher pressures

Lateral couplers Coupler 8 Extends or repairs 5/8-inch lateral tubing abovePunch 1 For installation of take-off connectors in 2-inch layflatIn-line filter 1 Sock-type filter and fittings for installation within 2-inch layflat1½-inch ball valve 1 Ball valve and short lengths of 1½-inch PVC pipe for use

with 2-inch layflat aboveElbows 2 Injection-molded 2-inch elbows for use between Water Basket and

groundInstallation guide 1 Illustrated step-by-step installation and users’ guide (Rowell and

Soe, 2012); formerly included with every drip set, but nowreplaced with an instructional brochure and installation video(DVD)

Sold separatelyx

‘‘Sin Pauq’’w treadlepump

Mostly PVC construction; easily elevated but with treadles onground

Water basket Durable and self-supporting walls; 200 gal capacity with outletfittings for easy connections to drip set

T-fitting Injection molded ‘‘T’’ for use with 2-inch layflat abovez1 ft = 0.3048 m, 1 inch = 2.54 cm, 1 mil = 0.0254 mm, 1 mm = 0.0394 inch, 1 gal = 3.7854 L.yMade from a mixture containing both linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE).xMost drip set components mentioned above also available for purchase separately.w‘‘Sin Pauq’’ = baby elephant.

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After completion of the drip lateralscreenings and preliminary farmers’field tests described above, we estab-lished another 60 demonstrations/trials on small farms within almost everyagroclimatic zone in the country fromlate 2007 to early 2008. Locations werechosen according to the interest of ourpromotion staff and the perceived in-terest of farmers in those areas. Micro-tube emitter systems were installed atmost sites while drip tape fromDas wasinstalled at about one-third of the sites,which had wells as their water source.

Unlike the previous year, ele-vated water tanks used for many ofthe 2007–08 on-farm demonstrationswere prototypes of what came to beknown as the Water Basket. All ofthese early demonstrations were cus-tom systems, which had to be installeddirectly by the authors together withlocal IDE field staff as the technologywas virtually unknown to both staffand farmers. Drip was installed ona wide variety of crops, including ninedifferent vegetables, six different fruitcrops, four different flower crops, andbetel vine (Piper betle).

This second series of on-farm trialswith various crops was more successfulthan the first with over half the farmercooperators showing genuine interestin drip. An in-depth survey of usersconducted in early 2008 indicated that61% liked the system and planned tocontinue using it next dry season.While these results were comparableto 50% to 60% continuation rates forfirst time drip users in Kentucky aftersimilar on-farm demonstrations (Com-modity Growers Cooperative Associa-tion, 1998), there were still perceptualand performance problems with thenew Myanmar system. Our survey in-dicated that the primary concern of 40%of new users was insecurity about theamounts of water applied (i.e., they didnot think drip could provide as muchwater as traditional sprinkler cans). Ourinstallation team discussed current andfuture crop water requirements withfarmers who were trying drip, oftenexplaining how equal amounts of watercould be applied with drip as withtraditional watering methods.

There were also cases of lack ofapplication uniformity, usually result-ing from less flow from emitters far-thest from the water tank. In addition,we recognized the urgent need formore drip irrigation training for fieldstaff and for drip-related educational

tools and materials to use in conjunc-tion with a strong and ongoing on-farm demonstration program.

An unexpected and frustratinghardware problem was the variablei.d. of lateral tubing purchased fromIDE-India. While reportedly con-forming to the international standard5/8-inch diameter, individual 100-mrolls of tubing varied widely, so muchso that laterals would often not fitIDE-India’s own or other commerciallateral-to-main take-off connectorsdesigned for 5/8-inch tubing. As webegan local manufacturing, we quicklydiscovered that lateral tubing requiredconstant sampling, testing, and vigi-lance to maintain uniform diametersand wall thickness.

IRON PROBLEMS. A more seriousproblem was first observed at a tubewell site in Hmawbi Township whereDas drip laterals had been installed ina farmer’s field. Emitters in theselaterals became completely blockedwith iron oxide precipitate within 1month of installation; the same prob-lem was observed at another site inKungyangon. We learned that ferrousiron is fairly common in well water inparts of Myanmar and routinely testedfor it after 2008. We feared thatwithout some simple solution to theproblem, drip irrigation might not bepossible in large areas of the country.

Fortunately, one of our field staffshowed us a solution to this prob-lem used by villagers in an area whereiron-contaminated drinking waterwas commonplace. It was well knownin that area that drinking water fromlocal wells could be ‘‘cleaned’’ by let-ting it pass through a simple containerholding burned rice husks obtainedfrom a local rice mill. This wasteproduct is widely available fromMyan-mar rice mills, many of which burn thehusks to heat boilers powering cen-tury-old stationary steam engines. Al-though themechanismof iron removalis unknown, the high pH of the ashtogether with its high surface area andperhaps even activated carbon are likelyinvolved (Das et al., 2007).

Dissolved iron levels above 1.5ppm are considered ‘‘severe’’ in termsof clogging hazard for drip irrigationin the United States (Lamont, 2012).Using a commercial iron test kit(model IR-18 for 0–5 mg�L–1; HachCo., Loveland, CO), we found thata 20-gal container of burned huskscould remove very high levels of iron

almost instantaneously as water passedthrough it. In our tests, water with5 ppm iron was reduced to 0–1 ppmafter passing rapidly through the filter.

Taking advantage of this localtechnique, we manufactured cheap20-gal containers made of plastic tarpmaterial with porous bottoms; thesewere filled with burned rice husks andsuspended between the pump outletand Water Basket. Drip is now usedextensively with these filters in areaswhere the problem is severe. Villagersalso showed us that well water sam-ples containing high levels of iron willinstantly turn black when mixed withgreen tea or crushed guava leaves(thus eliminating the need for animported test kit), a technique alsoknown by villagers in parts of ruralThailand (Settheeworrarit et al., 2005).

During the course of the firstseason, we observed emitter cloggingof Das tape, D-tape� (labyrinth flowpath emitter tape from Super Prod-ucts, Bangkok, Thailand), and evenmicrotube emitters from iron precip-itates from well water. While in mostcases Das and D-tape did not clogwhen used for a single season withiron-free well water, we decided notto continue to test or promote theselabyrinth/turbulent flow path emit-ter laterals. The decision was made inpart not only because of the risk ofclogging but also because of the near-term impossibility of setting up localmanufacturing for these or similarbuilt-in emitter products.

Growing satisfaction, 2008–09On-farm demonstration was the

cornerstone of our drip irrigation pro-motion program from the beginning,and it was our policy to give an in-terested farmer a drip set or partial setfree-of-charge in a new area in exchangefor his or her willingness to take owner-ship of all other aspects of crop pro-duction and marketing while providingus with a minimal amount of feedback.Over 300 such demonstrations andinstallations were conducted across thecountry during the 2008–09 dry sea-son. While most of the system compo-nents were sold to farmers alreadyconvinced of the value of drip, aboutone-third of new installations were pro-vided free-of-charge to farmers whohad never heard of it.

Our user survey conducted at theend of this season clearly indicatedgrowing satisfaction with the product

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and its performance with 79% nowreporting their intention to continueusing drip compared with 61% the pre-vious year. Perceptions also appearedto be changing as now only 10% ofusers surveyed reported that drip wasnot supplying enough water com-pared with 40% after the 2007–08season. Some of these farmers and ourstaff also benefited from the publica-tion of our first drip irrigation instal-lation and users’ guide (Rowell andSoe, 2009), an illustrated booklet withsimple start-to-finish instructions onhow to install and operate a small low-pressure drip system.

All of our installations now in-cluded components that we had de-signed and manufactured in-countryincluding a simple punch and con-nector system for joining drip lateralsto flexible pipe and an ordinary 1-inchplastic screen filter. We designed themain or submain-to-lateral connectorsboth to accommodate variable lateraltubing diameters and for easy installa-tion and good fit in locally availableflexible plastic pipe. The connectorswere also designed with large i.d. (10mm) to reduce friction losses andincrease flow at low pressures. Giventhe expense and difficulty of import-ing drip kits and components at thetime, we concluded that under theseconditions drip irrigation wouldnever become economical and

accessible to the majority of Myan-mar’s small farmers without access toinexpensive locally made products.

How much water?From the beginning of our dem-

onstrations, we encountered farmerperceptions that limited adoption.Myanmar farmers seeing—but not yetusing—drip irrigation invariably com-mented that the system could not pos-sibly supply enough water comparedwith their traditional methods of Asiansprinkler can watering or furrow/flood irrigation. Most farmers tryingdrip for the first time could not believethat the relatively low flow observedcould supply the needs of the crop;they also had no idea how much watershould be applied through a drip sys-tem. The on-farm demonstrations to-gether with discussions of crop waterneeds and drip application rates be-came important strategies to addressthese issues. The concept of a waterrequirement calculator was born in2009 out of these discussions withfarmers and their need for a simpleand inexpensive tool to estimate hor-ticultural crop water requirements.

We subsequently designed andconstructed circular laminated card-board ‘‘Water Wheel’’ calculators(Fig. 10) using local 30-year averagesof monthly evapotranspiration to-gether with simplified crop coefficients

based on either growth stages (vege-tables) or percentage of crop canopycover (fruits and tree crops). Details ofthe design of these tools will be pub-lished in a future paper. The primarypurpose of the Water Wheel was toenable field staff to quickly and easilyestimate water requirements for themost common fruits and vegetablesgrown in Myanmar. Field workerscould discuss these requirements be-fore, during, or after installation ofa drip system, providing farmers witha reasonable estimate or starting point.

Local manufacturing, sales,and promotion

MADE IN MYANMAR, 2009–10.After implementing significant systemimprovements based on the early 2009trials described above, the 2009–10dry season marked the launch of thefirst drip set made entirely inMyanmar.The set was designed for installationsof �4000 ft2 of vegetables or otherhorticultural crops with typical 4-ftrow-to-row spacings. This was a sizewe considered large enough for localcommercial plantings but small enoughto be affordable to smallholder farm-ers. The cost of the set at the time was�$20, although farmers had to buytheir own flexible pipe for main orsubmain lines at an additional cost of$10 to $15, depending on plot size. A

Fig. 10. ‘‘WaterWheel’’ water requirement calculators based on simplified growth stages and long-term evapotranspiration (ET)averages for vegetable crops (left) and on percent canopy cover and ET averages for fruit and tree crops (right). Designed byB. Rowell and made by Proximity Designs (Yangon, Myanmar) from 2009 to 2012.

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20% introductory discount was offeredthat year as an extra incentive to newcustomers.

IDE-Myanmar’s treadle pumps,Water Baskets, and main/submainpipes were sold separately but availablethrough the same field staff and privateag supply shops. It was decided not topackage and sell flexible pipe for mainor submains as this material was bulky,expensive to transport, and alreadyavailable in small hardware shops inmost parts of the country.

Over 500 of these drip sets wereinstalled by our field staff and agentsduring this first year of formal sales. Itwas decided to target former cus-tomers who already owned IDE trea-dle pumps. We assumed that manypump users would have earned extracash and might be more interested innew products based on their experi-ence with the pump and their re-lationship with our field staff. Thesefarmers, while not the poorest or themost risk averse, were much morelikely to try this radically new andunfamiliar technology than thosewith absolutely no spare cash (or indebt) or who were unfamiliar withIDE and its products.

This was also the first season inwhich we began offering productloans, and about half of drip sales wereas a result of these loans. But the loanprogram turned out to be a two-edgedsword, requiring a lot of time toadminister by field staff who mightotherwise have done more drip instal-lations and on-farm demonstrations.Free demonstrations continued onlyin areas that had not seen a drip sys-tem, and the majority of sets were soldby our field staff and dealer shops.Systemswere installed by our staff withthe full participation of the farmer, orin many cases, the whole family.

Questions about satisfaction withdrip and Water Baskets were includedin a new customer care survey of 200drip users conducted at the end of theseason. Respondents were given fourchoices of ‘‘unsatisfied,’’ ‘‘neutral,’’‘‘satisfied,’’ or ‘‘very satisfied’’ in an-swer to the questions, and 88% wereeither satisfied (37%) or very satis-fied (51%) with the ease of use ofthe product. More significantly, 91%reported that they had recommendeddrip to a friend or neighbor.

When asked about using hiredlabor for crop production before andafter drip adoption, 59% reported that

they had used hired labor before usingdrip while only 5% reported havinghired labor after drip adoption. Thesefarmers also reported that, before dripadoption, theymade an average of 119trips to the field daily with sprinklercans. This amounted to a daily burdenof carrying 4 t of water to the field ontheir backs. We know from this andcountless interviews with farmers thatthe elimination of this heavy labor andthe resultant time and energy savingswere their primary motivations foradopting drip.

COUNTRYWIDE EXPANSION,2010–11. Important changes in sys-tem components were implementedfor the 2010–11 dry season as a resultof tests conducted in Spring 2010.This drip set included the new Low-Loss screen filter (Fig. 8C and D)together with all new fittings/pipesconnecting the Water Basket to themain line. More importantly, our de-sign team launched the new and in-expensive plastic ‘‘Sin Pauq’’ (baby

elephant) treadle pump, the first suchpump designed for easy mountingabove an elevated tank but withtreadles on the ground. This combi-nation of Water Basket, Sin Pauq,and drip set (Fig. 5, right)—nowwith most components optimizedfor low-pressure operation—set thestage for rapid expansion of drip irriga-tion in 2010–11. This season also sawthe expansion of sales of individual dripcomponents for larger systems usingmotorized pumps.

Sales of drip systems jumpedmorethan 4-fold to over 2100 units duringthe 2010–11 dry season (Fig. 11Aand B); this number does not includea large amount of lateral pipe andfittings sold to customers who wereexpanding an existing drip set or mak-ing their own systems using our com-ponents. This can be attributed notonly to design improvements but alsoto a new emphasis on drip promotioncommunicated to field staff by Prox-imity Design’s leadership during the

Fig. 11. Annual (A) and cumulative (B) sales of low-pressure drip sets and separaterolls of lateral tubing sold by International Development Enterprises-Myanmar/Proximity Designs (Yangon, Myanmar) from 2007 to 2015. Sales of separate rollsof lateral tubing are expressed as drip set equivalents: each drip set contains threerolls of lateral tubing; 1 drip set equivalent = total number of separate rolls soldO 3.

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launchmeeting at the beginning of theseason. It was now clear that drip wasa product that was here to stay and thatall field staff were expected to activelypromote it and conduct at least five on-farm demonstrations in areas wheredrip had not been used before.

The provision of product loanswas also closely associated with thisseason’s expansion with over 70% ofdrip systems purchased with loans ad-ministered by the same field staff whowere promoting and installing drip.About this time, self-employed, inde-pendent village ‘‘agents’’ began doingdrip installations for small fees in someareas; sales were also boosted as a resultof our first serious efforts to train theseagents who in the past did only treadlepump installations. Many of them in-stalled drip on their own plots afterlearning how to set up and operatea small system during their trainingprogram in Yangon. Given properhands-on training, agents often be-came the first adopters in their com-munities where they were knownand trusted. Nearly all were farmersthemselves and helped begin the pro-cess of farmer-to-farmer observationand discussion, which resulted in fur-ther adoption without the same levelof promotional efforts required byour full-time staff. They no doubtmultiplied the capacity of full-timefield staff and were key players in theexpansion of drip.

ACCEPTANCE AND ADAPTATION,2011–14.New drip system sales roseagain in the 2011–12 dry season toover 3200 sets, although the increasewas smaller than the previous season’sexpansion, perhaps as a result of a de-cline in the easy availability of productloans. However, this season sawa large increase in sales of separaterolls of drip lateral tubing; 4800 rollsof lateral tubing, equivalent to thearea of 1600 drip sets, were sold in2011–12 (Fig. 11A) for expansion ofolder systems or for larger installa-tions using motorized pumpsets. Atthis time, inexpensive 4- to 5-horse-power gasoline pumps ($100 to $125)began to appear in Yangon markets,and we began getting requests fromstaff to help customers configure ourdrip components for larger, higher-pressure systems.

New drip set sales declined some-what in 2012–13 following introduc-tion of the 2-inch layflat and subsequentprice increase when the main/submain

pipe was included in the set for the firsttime. Sales of new sets rose again in2013–14 followed by what could bea decline in the current (2014–15)season, although this season’s sales fig-ures were incomplete at the time ofwriting; Proximity Design’s 2014–15drip set price was $37.50. Although it istoo early to say with any certainty, salesof packageddrip setsmight be decliningwhile sales of separate rolls of drip lateraltubing are static or increasing (Fig. 11A).This could be associated with the rapiddrop in treadle pump and Water Basketsales as farmers move from gravity-fedsystems to inexpensivemotorizedpump-sets (Proximity Designs, unpublisheddata).

Careful attention to appropriatedesign of all major components andprivate sector sales coupled witha strong on-farm demonstration andfarmer education program resulted inadoption of drip in almost all agro-climatic zones in the country withover 12,000 small farm drip systemsinstalled since 2008 plus the equiva-lent of another 10,000 sets in sepa-rate sales of drip lateral tubing (Fig.11B).

Conclusions and lessonslearned

On the basis of hundreds of con-trolled tests and on-farm demonstra-tions conducted from 2006 to 2012,we developed a robust small farm dripirrigation system simple enough to bemanufactured in Myanmar at low cost.Large enough for use on 4000 ft2

commercial plantings of flowers, fruits,and vegetables, theMyanmar drip set inits simplest form can function at pres-sures as low as 1–2 psi or �1/10th ofconventional drip operating pressures.

We created a market for not onlya new product, but also an entirelynew system of irrigation in Myanmar.Our drip systems have been used ona wide range of crops including 16different vegetables, 14 fruit crops, 5flower and ornamental crops, and 7crops grown for other uses such asbetel leaf, coffee (Coffea arabica), anda perfume crop. While refining eachcomponent to function well using verylow system pressure was important,this did not ensure success; successfulintroduction required long-term andaggressive extension and training pro-grams. It is also doubtful that a dripsystem in the Myanmar context would

have been successful during the firstdecade of the 2000s without con-current efforts by our design andmanufacturing teams to develop af-fordable water containers and inex-pensive and easily elevated treadlepumps to fill those containers.

In our experience, the concept ofdrip irrigation was just as difficult tosell as the hardware, at least in thebeginning. We devoted considerabletime and resources to develop trainingaids and tools which helped changeperceptions and simplified/explainedthe technology to both staff andfarmers unfamiliar with it. These in-cluded five illustrated extension guides,twowater requirement calculators, andseven videos (DVDs) published byIDE/Proximity Designs from 2009to 2013. Scaling up required an exten-sive network of dedicated, field-basedpromotion (extension) staff andprivateagents who could comfortably explainand demonstrate the technology inareaswhere it was previously unknown.Strong perceptual barriers were over-come with effective practical staff train-ing and many on-farm demonstrations(experiencing is believing). It was es-pecially important that these staff en-sured success of the first adopters sothat subsequent farmer-to-farmer dif-fusion could occur.

Often overlooked is the level oftechnical support/expertise requiredin such programs. This includes theability to train key staff and counter-parts, to solve problems as they inevita-bly arise, to experiment with systemchanges and to help produce appropri-ate educational tools and materials insupport of on-farm demonstration andtraining programs.

The importance of product loansor other farm credit cannot be under-estimated, especially in countries likeMyanmar where farmers have little ac-cess to low-interest agricultural loans.Although time consuming and difficultto manage, the product loans madeavailable to our customers after 2009accelerated adoption and helped ensuremore equitable access to the technology.

IDE/Proximity Design’s historyof introducing drip in Myanmar wasinitially one of slow growth: we tested,improved, and demonstrated customsystems built with imported pieces andparts while gradually substituting lo-cally made components as they weredesigned and manufactured. Only inthe final stages were drip sets or kits

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assembled and marketed with all lo-cally made components. We learnedduring the first season that wholesaleimportation of ‘‘drip kits’’ designed foran entirely different agricultural con-text was inappropriate.

It will be interesting to see hownewly imported commercial drip sys-tems will fare in the country followingthe recent lifting of trade sanctionsand whether they will be affordable tosmallholder farmers. It is likely thatmicrotube systems like ours will even-tually be displaced although questionsremain regarding clog resistance ofbuilt-in labyrinth flow path emittertapes under extremely low pressuresand relatively poor filtration from sim-ple screen filters. However, this mightnot be an issue if most Myanmarfarmers are transitioning to motorizedpumping systems.

Drip irrigation is still in its earlyadoption stages in many parts of thecountry and a generation may be re-quired before the technology is wellknown and widespread. This posesa challenge to donors expecting quickresults and impact from social enter-prises introducing new irrigation tech-nologies to raise small farm incomes.Any organization or company hopingto introduce drip in a country whereit was previously unknown should beprepared for a long-term commitment.This was also the case with small farmersin Kentucky where drip irrigation be-came common among horticulturalcrop growers only after a decade ofwell-supportedon-farmdemonstrationsby the Cooperative Extension Service.

It is hoped that lessons learnedand described here will help shortenthe time and effort required to in-troduce low-cost drip in similar so-cioeconomic settings. Adoption mayaccelerate inMyanmar as private com-panies begin marketing imported orlocally manufactured irrigation prod-ucts, although the challenge will stillbe to design and demonstrate simple,flexible, effective, and intuitive systemsthat are affordable to smallholderfarmers. In the meantime, ultra-low-pressure drip systems are now beingtested in conjunction with low-powereddirect-current pumps and solar (pho-tovoltaic) panels for horticultural

crops in India, Nepal, Myanmar, andwith high tunnels in Kentucky.

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Palada, M. and M. Bhattarai. 2012.Assessing technology and socioeconomicconstraints and prospects of low-costdrip irrigation for vegetable farming inSoutheast Asia, p. 154–167. Proc. HighValue Vegetables in Southeast Asia(SEAVEG): Production, Supply, andDemand. 21May 2015. <http://203.64.245.61/fulltext_pdf/EB/2011-2015/eb0197.pdf>.

Rowell, B. (ed.). 1999. Fruit and vegetablecrops research report. Univ. Kentucky,Dept. Hort., Publ. PR-423. 21 May2015. <http://www2.ca.uky.edu/agc/pubs/pr/pr423/pr423.htm>.

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