SUBSURFACE DRIP IRRIGATION FOR WATER TABLE CONTROL AND POTATO PRODUCTION

For three crop seasons (1995-1997), potatoes (Solanum tuberosum L.) were grown in the field to evaluate the use of an automatically controlled subsurface drip (SDI) irrigation system with conventional semi-closed seepage irrigation (subirrigation). Both the SDI irrigation system and the automated irrigation control system performed well, and crop yields produced exceeded the industry average each year. The field water table responded more quickly to irrigation with SDI, and the water table was more accurately controlled at the desired level. Potato yields were statistically similar with the two irrigation systems, although 36% less irrigation water was applied with SDI, despite water requirements for filtration and flushing to prevent emitter plugging. The continuous injection of a commercially available irrigation line cleaner prevented the buried irrigation emitters from plugging throughout the crop season. Emitter flow rate reductions occurred whenever irrigation was interrupted for extended periods of time, but flow rates recovered within days of the resumption of regular irrigations and chemical water treatment. Energy required for irrigation pumping was about 70% higher with SDI, despite lower volume of water applied, because the operating pressure was much higher than with seepage irrigation. Estimated cost to convert an existing seepage system to SDI is $990/ha.