Assessment of soil erosion and conservation on agricultural sloping lands using plot data in the semi-arid hilly loess region of China

Study region: Semi-arid hilly loess region of China. Study focus: The objectives of this study were to investigate soil and water loss on agricultural sloping lands and to evaluate the effectiveness of soil conservation practices in controlling erosion using plot data.Runoff and soil loss were measured from the short slope plots (SSP) (7. m long) and the long slope plots (LSP) (20. m long) at various slope angles as well as from cropland and soil conservation plots (SCP) under natural rainfalls. New hydrological insights for the region: The results revealed that runoff per unit area slightly increased with slope angle on SSP, but reached a maximum at 15° and then decreased with slope angle on LSP. Soil loss per unit area increased with slope angle on both SSP and LSP. An average of 36.4% less runoff but only 3.6% less soil loss per unit area was produced on LSP than on SSP. The S factor calculated using the slope factor equations in USLE/RUSLE was significantly greater than that estimated from the measured soil loss on the plots. Rainstorms with recurrence intervals greater than 2 years were responsible for more than two thirds of the total soil and water loss. The effectiveness in reducing surface runoff by five types of conservation practices was mixed. However, all the conservation practices yielded much less soil loss than cropland.