Furrow-irrigated chufa crops in Valencia (Spain).II: Performance analysis and optimization

Chufa (Cyperus esculentus L. var. sativus Boeck.) is a traditional crop in the Mediterranean region of Spain, where it is only furrow irrigated. This article analyzes the irrigation performance for this crop, conducting field studies over three consecutive seasons in Valencia (Spain). Irrigation schedule was based on the volumetric soil water content, which was measured with capacitance sensors. Infiltrability was measured with blocked-furrow infiltrometers. An area velocity flow module measured the water flow, the cross-sectional geometry of furrows was determined using furrow profilometers, and times for advance and recession were recorded. WinSRFR software was used to analyze every irrigation event, determining the application efficiency (AE) and distribution uniformity of the minimum (DUmin), and to optimize the combination of furrow inflow (q) and cut-off time (Tco). Average values obtained for AE were 30.1%, 25.6%, and 26.7% in 2007, 2008, and 2009, respectively, and the corresponding DUmin values were 0.54, 0.61, and 0.67. Optimized results showed that it is possible to reach AE and DUmin values up to 87% and 0.86, respectively. However, understanding the q-Tco relationship that maximizes both AE and DUmin is more important than knowing the specific values. A function that related q and Tco was obtained for the typical plot dimensions, and this was validated in 2011. Therefore, this function can be used in most of the plots in the cultivation area.