Assessment of erosion rates during rehabilitation of hardened volcanic soils (tepetates) in Tlaxcala

The emergence of tepetates (hardened volcanic ash layers) on the surface after erosion of the overlying horizon is widespread all over the Trans-Mexican Volcanic Belt, and in particular in the State of Tlaxcala where it covers 15% of the state surface. The rehabilitation of tepetates can be a solution to the lack of arable land and to environmental problems related to surface runoff and soil erosion. The purpose of this investigation was to evaluate the effect of organic farming on erosion rates and to determine the relationship between runoff, soil loss, rain erosivity (EI30), soil organic carbon (SOC), vegetation cover (V) and aggregate stability (AS), by multiple regression analysis performed for individual erosive events (36) and for cumulative annual values. Erosion and runoff rates were measured from 2003 to 2005 in fi ve farmer’s plots (580 to 2,020 m 2