Research on the effects of soil erosion on soil productivity has attracted increasing attention.Purple soil is one of the main soil types in China and plays an important role in the national economy.However,the relationship between erosion and the productivity of purple soils has not been well studied.The purpose of this research was to determine if soil depth,which is dependent on the rate of erosion,has an influence on crop yield and growth.Plot and pot experiments at different soil depths were performed.Results indicate that soils from different parental materials had different growth features and crop yields due to the differential fertility of the derived soils.The yield reduction rate increases exponentially with the depth of eroded soil(level of erosion).The yield reduction rate per unit eroded soil horizon(10 cm) is approximately 10.5% for maize and wheat. Research on the effects of soil erosion on soil productivity has attracted more attention.Purple soil is one of the main soil types in China and plays an important role in the national economy. However, the relationship between erosion and the productivity of purple soils has not been well studied. The purpose of this research was to determine if soil depth, which is dependent on the rate of erosion, has an influence on crop yield and growth. Plot and pot experiments at different soil depths were performed. Results from that soil from different parental materials had different growth features and crop yields due to the differential fertility of the derived soils. The yield reduction rate increases exponentially with the depth of eroded soil (level of erosion). The yield reduction rate per unit eroded soil horizon (10 cm ) is approximately 10.5% for maize and wheat.