Variabilidade espacial de atributos físicos e químicos em cambissolo e argissolo na região de Humaitá, AM.

Abstract

In Amazonian environment there are few studies that evaluate the spatial dependence of soil properties, especially in grasslands and forests. The objective of this study was to analyze the spatial variability of physical and chemical Cambisol and Alfissol under grassland and forest in the region Humaita, AM. We installed a sample grid for each study area, with dimensions of 70 x 70 m and regular spacing between sampling points 10 m. Soils were sampled at depths of 0.0-0.05; 0.05-0.10 and 0.10-0.20 m, in the depths of 0.0-0.20 and 0.40-0.60 m for soil textural analysis, totaling 64 samples per depth. The sampling points of the meshes were georeferenced with GPS device and altitude was measured with accuracy level for the construction of digital elevation model (DEM). In general, all attributes showed spatial dependence structure of moderate to strong. However, the higher spatial variability was found for the attributes of the area of unspoilt countryside, reflecting the variation in the shape of relief and vegetation cover that exposes the soil to climatic factors. On the other hand, the major ones were observed for the attributes of the forest area, expressing that environment stability. Despite the different environments present similar values of organic matter, aggregate stability was higher in the country compared to natural forest. However, the values of bulk density, soil resistance to penetration and macroporosity indicate deficiency in the quality of the soil that can cause constraints to growth and development of plants. Kriging maps were possible to visualize the distribution of soil properties in the study areas, as well as inferences about the correlation between attributes and those with the landform.