Erodibility Characterization in Degraded Area By Principal Components Analysis.

Erodibility is a factor that characterizes the vulnerability or susceptibility of soil to erosion, representing the processes that regulates the infiltration of water and its resistance to breakdown and transport of particles. In order to analyze the correlation for the following variables that determine erodibility (K factor), we applied the multivariate statistical method, principal component (PC), in the area of ​​the headwaters of the watershed Gambá stream, Monte Alto/SP, characterized by intense degradation. There were obtained 207 soil samples (0-20cm) in a georeferenced sampling grid, which were subjected to physical and chemical analyzes. We calculated the erodibility of the soil, which the estimated average was classified as high. The analysis was performed with two PC, which accounted for 68.17% of the variables contained in the original data set (PC1 : 41.59%; PC2: 26.58%). The variables were broken down into PC1: very fine sand (VFS), silt, with positive values​​, coarse sand (CS) and medium sand (MS) in contrast with negative values, where the VFS (0.798) and silt (0.759) associate directly with each other, and inversely to the CS (-0.862) and MS (-0,950), so extreme and positive values in PC1 indicate soil samples with high erodibility, while extreme negative values ​​indicate samples with low erodibility. Variables: fine sand (FS), clay, organic carbon (OC) and very coarse sand (VCS) were in PC2, independent of PC1, and the greater the amount of clay (0.701), OC (0.528) and VCS (0.574 ), the lower the amount of FS (-0.858), indicating an inverse relationship. Thus, the results show that the particle size characteristics of the soil favors the intensification of soil loss process, with an estimated average of 0.030 Mg.h.Mj^-1.mm^-1 for the study area, reaffirming the need for conservation practices mainly provide relief with steep slopes.