Adjustment of the AquaCrop model in maize with different levels of irrigation in southern Uruguay temperate climate conditions

Abstract

The AquaCrop model allows evaluating and designing irrigation strategies that improve the use of irrigation water. The objective of this research was to calibrate and validate the AquaCrop model for maize to the climatic conditions of southern Uruguay, with different irrigation water management. This model was calibrated and validated for corn using experimental data from irrigation trials with different deficit levels in three seasons, 2015-16 and 2016-17 (calibration) and 2014-15 (validation). Three maximum irrigation depths were evaluated: 3, 6 and 9 mm day^-1, and rainfed (rainfall only). The crop was parameterized for local conditions and water stress coefficients were adjusted. The calibration simulated the yield, biomass and soil moisture in the irrigated treatments with good performance. All the statistic indexes used to evaluate the adjustment between the observed and simulated data model indicated a good model performance, with the exception of the efficiency coefficient of the Nash-Sutcliffe (EF) model. The model underestimated the yield in the rainfed treatment (EF of -0.52) when root depth was limited to 0.7 m. However, the test soil allowed for greater radical exploration than the initially used. At 0.90 m root depth, the model was good at simulating the yields in the rainfed treatment, mainly in dry years (EF of 0.79). The model predicts the yield with good adjustment in different irrigation and rainfall situations if the stress coefficients are adjusted and the crop is properly parameterized, mainly the root depth.