Spatial variability of some soil physical properties in three soils of São Paulo, Brazil

Abstract

Volumetric core samples and loose soil samples were collected at 1 m interval in 10 m long transects, on three major soil groups in São Paulo, Brazil. The soil cores were used for soil desorption curves and the bulk density, and the loose soil was used for particle size analysis. The parameters obtained from the soil water retention model, bulk density and particle size values were submitted to geostatistical analysis to study the spatial variability through the examination of semivariograms and cross-semivariogram. The results showed that the scale of variation changes from soil to soil, with maximum variation for the Podzolic Soil with clay surface texture, from the northeast part of the state. For this soil also, the spatial autocorrelation was the most expressive. The variability of the soil desorption parameters was related to the particle size parameters. The geostatistical analysis results allowed establishing sample spacing for the soils studied, to allow for estimation at any finer spacing, with no bias and minimum variance.