黄壤旱坡地退耕还林还草对减少土壤磷流失的作用

在贵州中部黄壤旱坡地上 ,通过无界径流小区以及野外坡面径流小区试验 ,对退耕还林还草初期阶段旱坡地地表径流中水溶态磷和颗粒态磷流失量的变化进行了研究。结果表明 :退耕还林还草后黄壤旱坡地地表径流中颗粒态磷含量比相应的旱地减少 2 2 .17%～ 6 3.4 8% ,而水溶态磷含量也减少 3.0 3%～ 4 4 .2 9% ;退耕还林区土壤水溶态磷和颗粒态磷的流失量分别比玉米种植区减少 38.6 5 %和 35 .0 8% ,退耕还草区土壤水溶态磷和颗粒态磷的流失量分别比玉米种植区减少 5 3.4 2 %和 4 1.94 %。退耕还林还草一方面减少了肥料的施用量 ,另一方面能明显减少土壤磷的流失量 ,特别是水溶态磷的流失 ,退耕还林还草工程是减少土壤磷流失和控制非点源污染的有效途径。

Roles of Reducing Phosphorus Loss of Surface Runoff from Yellow Soil in Hilly Areas by De-farming and Reafforestation

The amount of particulate phosphorus and dissolved phosphorus loss in runoff from yellow soil of hilly areas by de farming reafforestation in Guizhou province were studied. Results showed that the contents of particulate P and ortho P respectively reduced 22.17%~63.48% and 3.03%~44.29% in surface runoff derived from de farming reafforestation lands than in that from farming lands and that the amount of particulate P loss in runoff decreased 35.08% or 41.94% from plots de farming and reafforestation the slope than from plots cultivated the slope, while the amount of dissolved P loss also reduced 38.65% or 53.42%. Therefore, de farming and reafforestation were an effective way to reduce phosphorus loss in the upland fields due to decrease the amount of phosphorus putting in the soils or putting out form the soils.