The effects of the spatial and temporal heterogeneity on the soil loss in an agricultural basin

Abstract

The effects of the spatial and temporal heterogeneity on the soil loss in an agricultural basin. The objective of this work was to calculate the soil loss (A) by the Universal Soil Loss Equation (USLE) in a basin located in Pampa Ecoregion (Argentina), considering the spatial heterogeneity of their landscape units and the temporal heterogeneity associated with an agricultural cycle. The landscape was represented by a mosaic of seven units: Agricultural of Deep Soils (ASP), Agricultural of Shallow Soils (ASS), Thalwegs in the Upper Basin (VS), Thalwegs in the Middle and Lower Basins (VMI), Hills and Natural Grasslands (CyPN), Headwaters Wetland (HC), and the Main Watercourse (CP). The monthly A values were estimated by the Universal Soil Loss Equation, which calculates the soil loss as the product between factors that consider the effect of the rainfall, the soil, the crops, the topography and the management practices on soil erosion. The landscape units under agriculture (ASP, ASS, VS, VMI and CP) showed mean A values between 1.9 and 0.5 t (ha month)^-1, significantly different from the estimated for the areas “CyPN” and “HC” (0.04 and 0.002 t (ha month)^-1, respectively). The factors’ combinations which describe the structure of the basin (soils, topography, crops) contributed to the spatial heterogeneity of A, and its temporal heterogeneity was mainly related to the seasonal dynamics of the rainfall. USLE implementation reflected the spatial and temporal interactions among the factors which determine A and cause different erosive responses among the landscape units of an agricultural basin