Validation and Sensitivity Analysis of the AquaCrop Model for Deficit and Surplus Water Management in Hybrid Maize

Abstract

The FAO's Land and Water Division created the water-driven model AquaCrop to model how various herbaceous crops' yields would react to water. As a vital component, water has drawn the interest of scholars and decision-makers worldwide. They came to the conclusion that using the AquaCrop model would help with strategic planning by providing precise production projections several months prior to harvest. On a worldwide scale, irrigated agriculture continues to be the primary sector that exploits fresh water. The study aims to conduct a validation and sensitivity analysis of the AquaCrop Model for deficit and surplus water management in hybrid maize. Field experiments were conducted at the Agricultural College and Research Institute, TNAU, Madurai, during summer, irrigated with different deficit irrigation treatments. The experiment was laid out in a randomised block design, and replicated thrice under sandy clay loam soil. Experiments consisted of seven treatments through drip system based on PE and ETc approach viz., regulated deficit irrigation (RDI) at 80 and 60 percent (T2 to T5), alternate deficit irrigations (ADI) at 80 and 60 per cent (T6 and T7), and conventional drip irrigation (CDI) at IW/CPE of 0.75 (T1) for comparison. The test crop of CO(M)H-6, a maize hybrid, was used. The AquaCrop model simulated and observed grain and biomass yield with water use efficiency (WUE). The validation efficiency of AquaCrop was tested by the statistical measures such as RMSE, NRMSE, BIAS, R2 and index of agreement (d). Sensitivity analysis was performed under deficit conditions by decreasing the irrigation amount by 25, 50 and 75 per cent and surplus conditions by increasing the irrigation amount by 25 and 50 per cent under both rainfall and no rainfall situations. Sensitivity analysis of deficit irrigation revealed that maize yield was reduced in all the water deficit conditions. Surplus irrigation has not had much influence on the maize productivity, irrespective of irrigation practices under rainfall conditions. It is concluded that the AquaCrop model can be used with a high degree of reliability in practical management, strategic planning of the use of water resources for irrigation.