Spatial variability of physical characteristics of dystrophic red latosol under conventional tillage at Selviria (MS)

Abstract

The research was conducted at the Experimental Station of UNESP-Ilha Solteira-campus, located in Selviria, Mato Grosso do Sul State, Brazil (20º 22’S; 51º 22’W). The objective was to study the spatial variability of some physical characteristics of a Dystrophic Red Latosol under conventional tillage with bean crop, in the 1999/2000 agricultural year, aiming at providing subsidy for agricultural research planning. The soil characteristics studied were: macroporosity (MA), microporosity (MI), total porosity (TP), bulk density (BD), penetration resistance (PR), and soil moisture (SM). The grid sampling was a total of 103 points, and the soil depths used to obtain the soil samples were zero to 0.05 m (surface) and 0.15 to 0.20 m (subsurface). Initial descriptive analysis of data was made through characterization of average, variance, coefficient of variation, coefficients of skewed and kurtosis, and frequency distribution. Subsequently, the spatial dependence was verified through the semivariogrames. The results indicated that the variability of the soil characteristics were: a) very high for PR in both depths, and for MA at subsurface; b) high only for MA at surface; c) intermediate for SM in both depths, and d) low for MI, TP, and BD in both depths. All characteristics studied showed spatial dependence, except for the MI in the surface. Therefore, in the surface layer the TP, BD, PR, MA, and SM showed the reaches, respectively, of 8.6, 13.1, 15.2, 15.8, and 18.4 m, whereas in the subsurface layer the BD, SM, PR, MI, MA, and TP showed, respectively, the reaches of 1.0, 9.1, 14.4, 18.4, 19.2, and 23.7 m