Funções de pedotransferência para predição da umidade retida a potenciais específicos em solos do estado de Pernambuco

Pedotransfer functions are equations used to estimate soil properties of difficult determination, based on other, more easily obtained soil properties. In spite of the considerable number of equations available to predict moisture retention to specific matrix potentials, these should not be used indiscriminatley,since most of them were developed in temperate climate soils, using data obtained by method that differ from the ones used in Brazilian laboratories. The objectives of this study were: (a) to develop pedotransference functions to estimate water retention at potentials between -33 and -1,500 kPa and water availability, using particle size distribution and global density data from soils of Pernambuco State, and (b) to compare the prediction efficiency of the new equations with similar equations available in literature. A database of 467 soil horizons from 98 soil profiles was used to develop the equations. The profiles were grouped, according to the Brazilian Soil Classification System, in 27 third category level classes (great group) The obtained equations showed worthwhile determination coefficients and low prediction standard error. Data grouping according to clay fraction, approximated development rate or textural class, did not improve the prediction capacity of the pedofunctions. The equations proposed in other works presented high prediction errors and are not recommended for soils of Pernambuco State.