SPATIAL VARIABILITY OF SOIL CHEMICAL ATTRIBUTES SUBMITTED TO DIFFERENT TYPES OF AGRICULTURAL USE IN THE CERRADO-AMAZON ECOTONE

Abstract

The knowledge of the spatial variability of the soil's chemical attributes increases the accuracy of fertility management. In this sense, the objective of this study was to characterize the spatial variability of chemical attributes in a Cambisol Haplastic Ta Eutrophic under different use types. The study was carried out in the municipality of Combinado - TO. To carry out the study, 40 soil samples were collected at a depth of 0-20 cm, in a grid with three meshes to represent better the conventional pasture 40x40m mesh, irrigated pasture 20 x 20 m, and livestock integration area 22 x 22 m. The chemical attributes of the soil were evaluated: pH, phosphorus, potassium, calcium, magnesium, exchangeable aluminum, potential acidity, cation exchange capacity at pH 7.0, saturation by aluminum, saturation by bases, and organic matter. It was observed that chemical properties are influenced by land use. Except potassium and saturation by base and aluminum, the other variables showed spatial dependence. They indicated that the number of samples was sufficient to map the study area, except phosphorus and organic matter, which indicates the need for a shorter distance between the sampling points to be detected, using geostatistics techniques. The chemical attributes were sensitive to the type of exploration and possibly to the process of soil formation. Thus, using geostatistics and the elaboration of isoline maps by kriging allowed the definition of soil fertility management zones.