• 关键词：农业非点源污染  土地利用方式  地表径流  养分流失  磷

• 基金项目：国家重点基础研究发展规划项目(No.G1999011806);中国科学院土壤与农业可持续发展国家重点实验室和日本国际农林水产业研究中心资助项目

• 高超
• 1. 南京大学城市与资源学系, 南京 210093; 2. 土壤与农业可持续发展国家重点实验室, 南京 210008; 3. 日本国际农林水产业研究中心, 筑波 30528686

• 朱继业
• 南京大学城市与资源学系, 南京 210093

• 朱建国
• 土壤与农业可持续发展国家重点实验室, 南京 210008

• 宝川靖和
• 日本国际农林水产业研究中心, 筑波 30528686

• 王登峰
• 南京大学城市与资源学系, 南京 210093

• 周娟娟
• 南京大学城市与资源学系, 南京 210093

• 高翔
• 南京大学城市与资源学系, 南京 210093

• 窦贻俭
• 南京大学城市与资源学系, 南京 210093

• 摘要：在太湖流域利用为期3年的田间试验研究了不同土地利用方式下的土壤侵蚀和径流磷流失特征.结果表明,径流量和土壤侵蚀量都是竹园<板栗园<蔬菜地<玉米-油菜轮作.旱耕地上玉米-油菜轮作和蔬菜种植条件下磷的主要流失途径为泥沙搬运,磷的年均流失量分别为2.67kg·hm^-2和2.79kg·hm^-2,而竹园和板栗园则分别只有0.28kg·hm^-2和0.66kg·hm^-2.土壤侵蚀和磷流失主要发生在6~8月降雨集中分布的梅雨和台风季节.旱地上板栗园与玉米-油菜轮作2种利用方式的经济收益接近,但前者土壤侵蚀和磷流失量分别只有后者的6.7%和24.7%,在太湖地区种植板栗是值得鼓励的土地利用方式.稻田水旱(水稻-油菜)轮作条件下,磷主要随农田排水流失,降雨时间和施肥等农事活动的间隔长短在很大程度上决定了磷的年流失量,3次最大的流失事件中磷的流失量可达到全年磷流失的70%以上.稻田水旱轮作方式磷的年均流失量为0.93kg·hm^-2,分别只有旱地玉米-油菜轮作和蔬菜地的34.8%和33.3%.因此,根据不同土地利用方式下磷输出量的差异及其季节分布特征合理调整土地利用格局,并在暴雨集中期尽量减少施肥和翻耕等农事活动,可以降低农田生态系统磷的输出.

• Abstract：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 Pexported 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 Plosses, 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 Plosses 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 Pexports. 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.

• Key words：agricultural nonpoint source pollution  land use  overland runoff  nutrient losses  phosphorus

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