Optimization of Deficit Irrigation Using the Cotton2K Crop Growth Simulation Model

Cotton2K is a process based crop growth simulation model that was developed to simulate yield response of cotton (Gossypium hirsutum L.) to irrigation in semi-arid regions. The objective of this study was to determine the best deficit irrigation strategy that increase water use efficiency and optimize yield in The Texas Rolling Plains. Cotton yield dataset of field experiments conducted from 2009 to 2012 on an Abilene clay loam soil (fine, mixed, superactive, thermic pachic Agriustolls) at the Texas AgriLife Research-Chillicothe Research station near Chillicothe, TX (34вк15' N, 99вк 30' W) were used for the model calibration and validation. The studies had different tillage treatments and irrigation regimes based on evapotranspiration (ET) replacement method (45%, 66%, 75%, 100%, and 133% ET). The model was calibrated for the soil and climatic conditions at the Rolling Plains. The calibrated model was validated using lint yield dataset from 2009 to 2012. Results showed that simulated and observed lint yield were similar and the regression line was not significantly different from the 1:1 line (slope=0.97, Pr>t=0.65; intercept=93.59 Pr>t=0.22). Cotton lint yield was simulated using 30-years of weather dataset. Irrigation strategies for simulations included replacing 40%, 60%, 80%, 100%, 120, and 140% of the ET according to the crop coefficient approach. In this presentation, we will present results of the simulation scenarios.