Comparação de Modelos para Determinação Indireta da Curva de Retenção de Água no Solo: Aplicação em Solos da Bacia do Arroio Taboão, RS
Soil capacity of retaining water is fundamentally important for physical processes studies involved with the soil-water system. Its representation is made by means of the retention curve, obtained in laboratory, with the use of specific equipments and collected samples, or indirectly in the field, employing tensiometers. The most common procedure consists in determining the retention curve in laboratory utilizing undisturbed samples and the Richards Chamber. Despite being well established, this method has the drawback of being time-consuming. In order to avoid this shortcoming, different methodologies have been proposed to permit obtaining the retention curve indirectly, being the pedotransfer functions some examples of them. The objective of this research was to evaluate the performance of two methods of this nature comparing their results to those obtained with the classic methodology. The evaluated methods were that of Arya & Paris (1981) e the two models proposed by Walczak et al. (2006). The data base was constituted of 78 undisturbed samples collected from nine soil types, being eight of them clayey soils, in the Taboao stream basin, in the region of the city of Pejucara - state of Rio Grande do Sul. The obtained results have showed that all models systematically underestimated the soil moistures when compared to those measured in laboratory. In 65 % of the analyzed samples, the models proposed by Walczak et al. (2006) provided better performances than the model of Arya & Paris (1981)