The objective of this study was to evaluate the performance of simplified and agrometeorological models in the soybean crop productivity estimate, looking for crop season prediction and planning, in the Ponta Grossa region, Paraná State, Brazil. The soil of the studied region is classified as Typic Hapludox and the climate as Cfb. The soybean crop productivity (11 seasons) and climate data were provided by the ABC Foundation and SIMEPAR, respectively. The reference evapotranspiration was estimated by the Penman-Monteith method and the daily water balances were determined using a program especially developed for this purpose. After innumerable analyses, the best results were obtained when the following were considered: (a) the temporal distribution of real productivity of soybean crop seasons in two groups, which were called 'Year 1' and 'Year 2', according to the experimental crop rotation (b) the fit of model coefficient and factors to multiple regression analyses. The Stewart et al. (1976) and Jensen (1968) models provided the best productivity estimates (R² > 0.73).
crops planning; Glycine max; water balance
