Degradation of Soil Nutrients in Southeast China

摘要

A total of 2190 soil nutrient data in the Second National Soil Survey of China were collected to assess the rndegradation of soil nutrients in the hilly region of Southeast China. The definition of soil nutrient degradation rnis suggested firstly, then the evaluation criteria are set up and the current status of degradation of red soil rnand latosol is assessed. The percentages of areas in four grades of soil nutrient degradation, i.e., slightly rndeficient, medium deficient, severely deficient and extremely deficient, were 21.3%, 43.3%, 16.2% and 3.0%rnfor soil total N; 0.7%, 6.4%, 16.7% and 76.2% for soil available P; and 25.4%, 26.3%, 8.6% and 5.0% for rnsoil available K, respectively. The severity of soil nutrient degradation was in the order of P ＞ N ＞ K. The rnmajor factors leading to the degradation of soil nutrients in quantity include soil erosion, leaching and the rnconsumption by crops. And the principal factor affecting the degradation of soil nutrients in availability is rnthe fixation of N, P and K, especially the fixation of phosphorus. The average amount of P fixed by soils is rn408 mg kg-1, and upland soils can fix more P than paddy soils.