AquaCrop model assessment for simulating soybean response under water stress /Avaliação do modelo AquaCrop para simulação da resposta da soja sob estresse hídrico

Lately, irrigated soybean production has increased; therefore, tools that can aid water resources management must be improved. Two experiments were carried out, the first one from May to August and the second one from September to December 2019. The experimental design included randomized blocks with five treatments and four replicates. In the control treatment (SE), irrigation was carried out to meet the crop's water demand during all growth stages. In the other treatments, irrigation was interrupted at specific crop growth stages (TI = VC-V4, TII = V5-R1, TIII = R1-R5, and TIV = R5-R7), and then restored. After calibration, the model satisfactorily estimated the canopy cover, biomass, and soybean yield, with high values of determination coefficients ([r.sup.2] > 0.90), low RMSE and MBE values, and high values of EF. In experiment 1, the soil water content was overestimated in the SE, TI, and TIV treatments by 0.24%, 0.78%, and 0.23%, respectively, and underestimated by 3.3% and 5.5% in the TII and TIII treatments, respectively. In experiment 2, in the SE, TI, TII, TIII, and TIV treatments, the soil water content was underestimated by 6%, 3%, 4.6%, 5.9%, and 6.7%, respectively. Real evapotranspiration was overestimated in all treatments in both experiments, with low [r.sup.2] values in both experiments 1 (0.11- 0.23) and 2 (0.04 - 0.21). Key words: agricultural management, irrigation management, soil water content modelling, crop evapotranspiration. Ultimamente, a produção de soja irrigada tem aumentado, portanto, ferramentas que auxiliem na gestão dos recursos hídricos devem ser aprimoradas. Foram realizados dois experimentos, o primeiro de maio a agosto e o segundo de setembro a dezembro de 2019. O delineamento experimental foi em blocos casualizados com cinco tratamentos e quatro repetições. No tratamento testemunha (SE), a irrigação foi realizada para atender a demanda hídrica da cultura durante todas as fases de crescimento. Nos demais tratamentos, a irrigação foi interrompida em determinados estádios de desenvolvimento da cultura (TI = VC-V4, TII = V5-R1, TIII = R1-R5 e TIV = R5-R7) e, a seguir, restabelecida. Após a calibração, o modelo estimou satisfatoriamente a cobertura do dossel, a biomassa e a produtividade da soja, com altos valores de coeficientes de determinação ([r.sup.2] > 0,90), baixos valores de RMSE e MBE e altos valores de EF. No experimento 1, o teor de água do solo foi superestimado nos tratamentos SE, TI e TIV em