Water retention estimation and plant availability for subtropical Brazilian soils

Limited databases on water retention and availability in soils to generate pedotransfer functions are available for tropical and subtropical soils. The objectives of the study were to generate and evaluate pedotransfer functions for soil water retention in soils from subtropical Brazil; and to estimate plant available water based on soil particle size distribution. Two databases were set up for soil properties including water retention: one had 725 data and the other 253 data. From the literature database, pedotransfer functions were generated, nine pedofunctions available in the literature were evaluated and the plant available water capacity was calculated. Pedotransfer functions for selected sections generated for the soils had coefficients of determination ranging from 0.56 to 0.66. Pedotransfer functions generated with soils from other regions were not appropriate for estimating the water retention. Plant available water content varied with soil texture class, from 0.089 kg kg-1 for the sand texture class to 19.6 kg kg-1 for the silty clay class. These variations were more dependent on sand and silt content than on clay content. The soils with a greater silt/clay ratio, that were less weathered and had a greater quantity of smectite clay minerals, possessed greater water retention and plant available water capacity