In order to study sampling techniques useful for digital soil mapping (DSM), we evaluated the effect of changes in sampling density, based on data from areas already mapped by traditional methods, in regard to the accuracy of decision trees models for generating soil maps using DSM. In two watersheds in northwestern Rio Grande do Sul, Brazil, 1:50,000 scale conventional soils maps were used as reference maps. From the ASTER – GDEM Global Digital Elevation Model and the hydrographic network, maps […]

Hydro-sedimentologic models are useful in the environmental analysis of unmonitored watersheds. However, the models must be calibrated and validated for accurate predictions. The objective of this study was to calibrate MUSLE for the conditions of the Piripipau river basin (Brazil), using hydrologic and sedimentologic data from 1999 to 2005, and to validate the calibrated model with another data set (1998, 2006-2009). MUSLE’s a coefficient was calibrated fitting observed and calculated sediment yield values of individual events, using observed hydrologic data […]

Soil resistance to root penetration is an important physical characteristic for defining soil management techniques. The purpose of this study was to estimate the mechanical soil penetration resistance of an Oxisol under perennial crop, at three gravimetrical moisture contents, based on bulk density, moisture, and soil clay and organic matter content. The soil penetration resistance was evaluated by an impact penetrometer and the impact data in dm-1 were converted into dynamic resistance (MPa). At the moment of the determination of […]

Interactions between P and S anions and soil colloids are significant, mainly those rich in iron and aluminum oxides, whose electric surface charges vary according to the pH and ionic strength of the solution. The objective of this study was the evaluation of phosphate and sulfate adsorption on surface and subsoil samples of a clayey Anionic Acrudox, a medium-textured Anionic Acrudox and a clayey Rhodic Kandiudalf from the northern region of the State of São Paulo, Brazil. Maximum phosphate and […]