Performance of 37Cs fallout redistribution analysis, USLE and WEPP as erosion prediction technology in a complex landscape watershed under sugarcane cultivation

Sail erosion is the main degradation process in tropical agroecosystems. Most erosion prediction methods are not sufficiently calibrated for tropical conditions. Thus, differences in estimated soil erosion values may be expected for the same input data, Three soil erosion estimation methods (USLE, WEPP and Cs-137) were applied to the same watershed cultivated with sugarcane in Brazil. The absolute erosion rate values and the differences in the spatial distribution were evaluated. The results suggested that there arc important differences in soil loss estimated by the methods. The differences occurred in both mean values and spatial distribution. The sequence of mean soil loss values was USLE>>Cs-137>WEPP and standard deviation values USLE>WEPP>Cs-137, indicating that USLE predicted the highest erosion rates that were spread out over the widest range. The poor spatial erosion prediction results observed in this study suggest that uncalibrated soil erosion prediction methods should be used only in qualitative applications.