Spatial variability of the primary fractions and aggregate of an Ultisol in the State of Ceará, Brazil

Abstract

The spatial variability has been one of the concerns of researchers since the beginning of the century, being the soil management system a factor that interferes in the spatial distribution of the physical properties of the soil. The objective of this research was to characterize and determine the spatial variability of physical attributes of an Alfisols, by using geostatistical methods and surface maps using the Kriging interpolation method, at two soil depths. Soil sampling was performed following a 2.5 x 2.5 regular grid, in an area of 400 m², with a total of 81 points in each one of the soil depths (0-0.2 m and 0.2-0.4 m). The 162 samples were subjected to the physical analysis and the data was tested for normality using descriptive statistics and later submitted to the geostatistical analysis. The spherical semivariogram model was the best fitting, for most of the variables. Random variance was verified for the variables flocculation degree, at the 0-0.2 m depth and aggregate stability at the 0.2-0.4 m depth.