On-farm trials and demonstrations of low-cost drip irrigation systems for fruits, flowers, and vegetables were carried out with hundreds of farmer cooperators by the nonprofit organization Proximity Designs (Yangon, Myanmar) from 2007 to 2009 before launching the country’s first locally designed and manufactured drip system in Nov. 2009. Over 20,000 of these small farm systems had been sold by the end of the 2015 dry season (Rowell and Soe, 2015).
From the beginning of these demonstrations, we encountered farmer perceptions that limited adoption of drip. Myanmar farmers seeing—but not yet using—drip irrigation for the first time invariably commented that the system could not possibly supply enough water compared with traditional methods of sprinkler can watering or furrow/flood irrigation. Most smallholder farmers trying drip for the first time could not believe that the relatively low water flow observed from emitters could supply needs of the crop.
Local farmers initially had no idea how much water should be applied through a drip system and could not afford simple tensiometers, much less more sophisticated soil moisture monitoring tools or computer software; none had access to personal computers or mobile phones at the time. On-farm demonstrations together with one-on-one discussions of crop water needs and drip application rates became important strategies to address this issue. The idea of a simple paper calculator was born out of these discussions with farmers and their need for an easy-to-use yet inexpensive tool to estimate horticultural crop water requirements. This paper describes concepts and design of two different Water Wheel calculators in enough detail that nonspecialists might develop their own calculators using local climatic data. It is also hoped that this will stimulate further experimentation, discussion, and generate suggestions for improvement.
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