Effects of water and soil conservation practices on reducing pollution from agricultural nonpoint source in Northeast China

Soil and water loss from sloped farmland is a mainly environmental and agricultural issue worldwide. Many management practices have been selected and are effective to reduce sediment and associated nutrient losses. Fallout Pb-210(ex) tracer technique was used to quantity the soil erosion in terrace cultivation and contour farming field. The soil erosion rate from up-and-down slope field was estimated by RUSLE2 model. The sediment yields from contouring and terraces were reduced 63% and 95%, respectively, by comparison with up-and-down tillage. Terraces could reduce soil erosion 74% and intercept runoff 45% than contouring tillage. However, the concentrations of nitrogen and phosphorus with runoff from terraces were greater than those from contouring field. Transport loads of TP, DTP, and phosphate (PO43--P) through water from terraces increased 4.54, 1.34, and 2.53 times than those from contouring tillage, respectively. It is concluded that no single mitigation option can reduce all pollutants. Terrace can achieve pollutants reduction target in tandem with other soil and water conservations.