The spatial variability of soil physical and chemical attributes presents direct relation with the formation and maintenance of soil aggregates. However, the different soil management systems also interact with these attributes modifying their natural variability. Thus, the objective of this work was to study the spatial variability of the physical and chemical attributes of two Oxisols of the State of São Paulo, under no-tillage system and its relation with the aggregate stability. The soil samples were collected in the 0.0 - 0.1 m depth, at the nodes of sampling grid of 100 m between points. One of the areas is located near Angatuba, SP, Brazil and the other one in Campos Novos Paulista, SP, Brazil. The physical attributes analyzed were: clay content, coarse, fine and total sand contents and the weighed mean aggregate diameter (DMP) as an indicator of aggregate stability. The soil chemical attributes studied were: organic matter, calcium and magnesium contents. The data were analyzed using descriptive statistics and geostatistics tools. Once the spatial dependence has been detected by means of the semivariogram contour maps were constructed using the kriging interpolation technique. The spatial variability for the chemical and physical attributes and their relation to the aggregate stability was influenced by past management history of the areas studied. The Oxisol in Campos Novos Paulista had lower nugget effect (C0) values. The spacing used in Oxisol in Campos Novos Paulista was not sufficient to detect the spatial dependence of DMP.
geostatistics; soil tillage systems; soil physical; soil chemical; soil quality
