Dual crop coefficients for maize in southern Brazil: Model testing for sprinkler and drip irrigation and mulched soil

The study sought to determine the appropriate basal crop coefficients for maize through the calibration and validation of the model SIMDualKc using various treatments of maize irrigated with sprinkler and drip methods under full and deficit irrigation and cropped with organic mulch. The model computes crop evapotranspiration (ETc) using the dual crop coefficient methodology, thus separating crop transpiration, Tc, and soil evaporation, Es. Two experiments were carried out and the model was calibrated for one treatment of each experiment and validated with the remaining treatments. The corresponding results show good agreement between the simulated and observed available soil water through the season, with regression coefficients of 0.99–1.02, and the root mean square error ranging 2.0–3.3% of the total available water. The calibrated Kcb for the initial and mid-season are respectively 0.20 and 1.12; the Kcb at end season is 0.2 for grain maize and 0.8 for maize harvested for silage. Results show that the evaporation component of evapotranspiration is less than 9% of ETc for both sprinkler and drip experiments, thus indicating the suitability of using mulch for water conservation.