Nutrient Losses in Soils on Loess Plateau
摘要
The soil nutrient losses due to excessive soil loss on Loess Plateau were studied by means of runoff plotsand systematical determination of soil nutrients both in sediments and runoff.The results show that theamounts of nutrient losses depended on the amounts of erosion sediments. Along with sediment, 11-197 kgnitrogen/hectare and 9-174 kg phosphorus/hectare were lost, accounting for 92.46-99.47 percent of the totalamount of nitrogen loss and 99.85-99.99 percent of the total amount of phosphorns loss respectively. Thenutrient losses, very small in runoff, were mainly attributed to erosion of a few rainstorms during a year. Thenutrient level in sediment was mostly higher than that in the original soil. Planting grass evidently reducedthe losses of soil nutrients. The N level was lower in runoff than in rainfall so that the N loss from runoffconld be made up by rainfall. Fertilizer application to crops raised the nutrient level in runoff.