Abstract

Soil water content (q), bulk density (r_b) and associated properties greatly influence important soil and plant processes. A field experiment was carried out in Mococa, São Paulo, Brazil, in a lowland area with the objectives firstly, to assess the spatial variability of selected soil propertiesq, r_b, total porosity and microporosity using classical and geostatistical techniques and secondly, to find out how they are correlated. Results generally showed that at 0 to 20 cm depth, q at saturation and 5 cm were negatively skewed but positively skewed at the rest of the remaining depth of testing. On the other hand, kurtosis values were not consistent but were positive in both the top and subsoil. This implies that in both depths, tested parameters were highly variable and were not normally distributed. In top soil, only water at 1000 cm pressure and bulk density had negative skewness and kurtosis values. The values for nugget, sill, % nugget or randomness degree, and range for r_bdecreased with depth also showing lower structured range which probably signifies that there was no depositional material on this site. To conclude, firstly, the spatial variability of most properties was moderate and the majority of soil properties were well described using spherical or exponential mathematical models. Secondly, the distances at which variables were correlated in the top and in the subsoil showed minor differences. Thirdly, semi-variance analyses in top and sub soils showed that differences exist in the patterns of spatial variability, with the sub soils showing strongest spatial dependence.

Key words: Spatial variability, soil water content (q), bulk density (r_b), microporosity, geostatistics.