Dados do Trabalho

Título

BUCKET MODEL VERSUS RICHARDS EQUATION-BASED MODEL TO PREDICT TRANSPIRATION FLUXES AND DROUGHT STRESS IN SOYBEAN

Resumo

Opposed to Richards equation-based models, bucket models for soil-water balance simulation do not include a process-based description of soil water dynamics. This implies differences in the computation of the soil-water balance and the prediction of drought stress with possible implications on crop productivity. This study aimed to compare the predictions of two agro-hydrological models, WOFOST (bucket-type) and SWAP (Richards equation-based), in a scenario with soybean in Piracicaba, southeast Brazil. Crop growth was simulated for 35 years using meteorological data measured between 1988 and 2022, using four soils of the region (Nitisol, Acrisol, clayey Ferrasol, sandy Ferrasol) and four sowing dates (Nov 14, Nov 26, Dec 14, Dec 26). WOFOST and SWAP used the same detailed crop growth module previously calibrated and validated for soybean. Model parameters related to soil hydraulic properties were obtained by inverse modeling considering homogeneous soil profiles. Some functionalities available in SWAP which are not equally available in WOFOST were disabled: crop water interception, salt stress, stress due to management and irrigation. The SWAP model simulated higher rates of potential and actual transpiration and predominantly higher averages of crop productivity. In some seasons simulated by WOFOST, the crop died before maturity due to severe drought stress expressed by leaf abortion. In contrast, WOFOST simulated higher values of crop productivity under favorable conditions (sufficient rainfall). For both models, the best and the worst crop performance were obtained for the Acrisol scenario starting on Nov 14 and the clayey Ferrasol scenario starting on Dec 14, respectively. The different model approaches to simulate soil water dynamics and transpiration fluxes were determinants for the prediction of drought stress and productivity of soybean, which may imply divergences in recommendations for crop management.

Palavras-chave

WOFOST model; SWAP model; soil water dynamics; Glycine max (L.).

Instituição financiadora

São Paulo Research Foundation (FAPESP, 2020/07294-3 and 2022/03770-0).