Scheduling Irrigation on Non-Flooded Rice

Abstract

While continuous-flood irrigation, the most common method for US rice production, can have a fairly high application efficiency, factors such as soil variability and the size of most Mid-South farming operations combine to reduce the efficiency in many cases. Center pivot irrigation is one potential way to reduce water use in some cases and bring rice into the crop rotation in other situations. Rice was produced at the University of Missouri Delta Research Center Marsh Farm at Portageville in 2009 and 2010 and irrigated every other day with a 150-m-long center pivot irrigation system. An experimental crop coefficient function was developed and included in a beta version of the Arkansas Irrigation Scheduler to estimate the daily soil water deficit (SWD) and daily short grass reference evapotranspiration (ETo) was calculated from weather data collected on site. Weather conditions were warmer and much drier in 2010 and ETo was higher each month. In 2009, there were a total of 34 days with irrigation and 414 mm of water applied. In 2010, there were a total of 45 days with irrigation and 503 mm of irrigation water applied. The AIS appeared to respond as expected with the frequent irrigation; therefore, the next phase of the project will use the beta version of the AIS to schedule irrigations based on allowable SWD. The findings should indicate whether the current crop coefficient in the AIS is adequate and allow producers a system for scheduling center pivot irrigation on rice.