The agrometeorological models allow better knowledge of the quantitative influence of the climatic conditions, such as drought effects on the soybean development and grain production. A good model requires the evaluation of the sensitivity indices and test for a specific variety and region. Phenological and yield data were taken from planting date experiments conducted at Ribeirão Preto, Instituto Agronômico Experimental Station during four growing seasons. Three cultivars were considered according the maturation group: IAC-13 (early), IAC-12 (semi-early) and IAC-11 (median). Additive and multiplicative type models were tested based upon the penalization of the crop yield potential according the ER/EP relation (actual/potential evapotranspiration) and water excess, derived by a 10-day soil water balance, occurred during four growth stages. Based on the model's statistics, additive and multiplicative type models presented similar performance. The model which considers penalization including water excess presented the best performance for the three maturation groups, with R2 of 0.69 and d-index of agreement of 0.85 for the IAC-13 (early) cultivar; R2 of 0.72 and d-index of 0.73 for the IAC-12 (semi early) cultivar; and for the IAC-11 (median) cultivar, R2 of 0.79 and d-index of 0.73. Index terms: soybean, growth stage, soil water balance, agrometeorological models, crop production.
