Comparison between direct and indirect methods for the determining the erodibility in latosols under cerrado vegetation

Abstract

This study had the objective of comparing the soil erodibility obtained through six indirect methods with the direct one, determined under field conditions with rain simulator, in Dark-Red Latosol (LE) and Red-Yellow Latosol (LV) under cerrado vegetation. Beyond the necessary analyses for the index calculus, the amounts of total free (DCB) and sulphuric attack iron, and kaolinite and gibbsite in the freeiron clay fraction and the light/heavy minerals ratio in the sand fraction were also determined. It was concluded that the indirect methods are not statistically exact in relation to the direct one for estimating an absolute value for the erodibility factor. In spite of this inexactness, the VI method is the one which is nearest to the standard in terms of erodibility proportion for the studied latosols. The obtained erodibility indices fit the LE in the very low ( < 0.013) and the LV in the low class (0.013-0.033) of susceptibility to hydric erosion. The LV presented losses well above its tolerance maximum limit, in the summer period, indicating the need of adequate conservation practices for reducing such losses.