Soil Physical Attributes Affected by Crop Systems and Materials for Acidity Correction.

This research was conducted aiming to evaluate the effects of crop systems and materials for acidity correction on soil physical attributes between October/2006 and July/2008, in Botucatu-SP, Brazil. The experimental design was the completely randomized block, with subdivided plots and eight replications. Plots consisted of four crop systems, as follows: I-soybean/fallow/maize/fallow; II-soybean/white oat /maize/common bean; III-soybean/millet/maize/cowpea; IV-soybean/signal grass/maize/signal grass. Subplots were defined by superficial liming and silicon application, to raise base saturation up to 70%, and a control. Aggregate stability, soil density, total porosity, macroporosity and microporosity were determined. Soil penetration resistance and moisture were also evaluated. Means were compared by the t test (LSD) at a probability level of 5%. Superficial application of materials for acidity correction increases soil total porosity, accentuated down to 0.20 m and 0.10 m after silicate and lime application, respectively. Soil structuring is harmed by the cultivation of only a crop per season, decreasing aggregate stability and increasing penetration resistance in superficial soil layers. Signal grass cultivated between summer crops increases aggregate stability-index down to 0.10 m the soil profile.