Phosphorus exports via overland runoff under different land uses and their seasonal pattern
Phosphorus exports via overland runoff under different land uses and their seasonal pattern
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发表时间：
2005
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通讯作者：
G. Chao;Zhu Jiye
中科院分区：
文献类型：
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作者：
G. Chao;Zhu Jiye
以太湖流域为例，研究了不同土地利用方式下侵蚀区坡面径流泥沙和磷素的流失规律。径流量和侵蚀速率的大小顺序为竹林果园菜田玉米/油菜轮作，磷素的输出顺序为竹林果园玉米/油菜轮作菜田。沉积物附着的磷占大部分的玉米/油菜轮作和蔬菜田的磷输出，表明侵蚀控制是最有效的方式来减少磷流失的旱地。磷素流失具有明显的季节性特征，60.9%~84.7%的磷素流失发生在季风和台风季节（6 ~ 8月）。不同土地利用的成本效益分析表明，板栗和玉米/油菜轮作提供了类似的经济回报。从水土流失和磷素流失的风险考虑，在太湖地区发展板栗种植有利于控制面源污染。油菜/水稻轮作稻田土壤磷素主要通过径流和排水输出。磷素年流失量主要取决于降水量及其与施肥的配合程度。施肥后立即发生的三次强降雨事件占全年磷出口量的70%。研究结果表明，通过优化土地利用方式和减少敏感时期的耕作措施，可以显著减少农田生态系统磷素的输出。
Sediment and phosphorus losses via overland runoff from erosion plots under different land uses were studied in an agricultural watershed in the Taihu Lake area in eastern China. Runoff and erosion rates followed the order of bamboo forest chestnut orchard vegetable field corn/rapeseed rotation, while phosphorus exportation followed the order of bamboo forest chestnut orchard corn/rapeseed rotation vegetable field. Sediment attached phosphorus accounted most of the P exported under corn/rapeseed rotation and vegetable fields, indicating that erosion control was the most effective way to reduce phosphorus losses from uplands. Distinct seasonal pattern of phosphorus losses was observed, with 60.9%～84.7% of annual phosphorus loss happened during monsoon and typhoon season (from June to August). Cost/benefit analysis of different land uses showed that chestnut and corn/rapeseed rotation provided similar economic returns. Considering the risk of soil erosion and P losses, chestnut farming was worth encouraging in Taihu Lake region for the benefit of non-point source pollution control. For the paddy field under rapeseed/rice rotation, phosphorus was mainly exported with runoff and drainage water. Annual P losses were mainly decided by the amount of precipitation and its coincidence with fertilization. Three heavy rainfall events immediately following fertilization accounted as high as 70% of annual P exports. The results of this study indicated that phosphorus exports from agro-ecosystem could be significantly cut down by optimizing land use patterns and by reducing tillage practices during those sensitive periods.