小麦/玉米轮作体系中不同施肥方法下的养分淋溶排污系数测算

Calculating Discharge Coefficients for Soil Nutrients in Wheat-Maize Rotation System Under Different Fertilization Practices

为粮田耕地污染监控预警及污染控制提供技术支持,以北京市房山区小麦/玉米轮作为研究对象,采用陶土头负压法,通过2年的田间小区对比试验,以不施肥处理为对照,分析比较优化施肥和常规施肥对淋溶液水质的影响,并测算不同施肥处理的排污系数。研究结果表明:不同的施肥处理氮素淋溶量占总养分淋溶的76%~82%,氮素淋溶中以硝态氮为主,占总氮素淋溶的60%~70%,最高可达到90%;在氮磷钾养分施入量相同的情况下,优化施肥处理在不同程度上降低了养分淋溶量,可使总氮淋溶量减少23%~31%,总磷淋溶量减少32%~46%,硝态氮淋溶量减少22%~36%,在降雨量大时,优化施肥处理可明显减少铵态氮的淋溶;经测算,小麦/玉米轮作农田耕地排污系数(产出每公斤农产品养分淋溶排出量)常规施肥处理总氮、总磷、铵态氮及硝态氮的排放量分别为687.2、3.25、0.22、440 mg,优化施肥处理的排放量分别为348、0.87、0.38、205.9 mg。

In order to find out nutrient leaching from different fertilization practices, a two-year nutrient leaching experiment was designed in a wheat-maize rotation farmland in Fangshan district, Beijing. Nutrient leaching was measured in optimized fertilization, traditional fertiliza-tion and no fertilization(control)fields using vacuum negative pressure. Results showed that TN leaching was accounted for 76%~82% of total nutrient leaching for all treatments. Nitrate nitrogen was the main component of TN losses, accounting for 60% ~70% of TN leaching,with the highest of 90%. At the equal amounts of NPK, the optimized fertilization reduced TN leaching by 23%~31%, TP leaching by 32%~46%, and NO-x-N leaching by 22%~36%, compared with traditional fertilization. The reduction of NH+4-N leaching by the optimized fertilization was more significant under greater rainfall. In wheat-maize rotation system, the discharge coefficient of production per kilogram agricultural products for TN,TP, NH+4-N and NO-x-N was 687.2 mg, 3.25 mg, 0.22 mg and 440 mg for traditional fertilization and 348 mg, 0.87 mg, 0.38 mg and 205.9 mg for optimized fertilization, respectively. These results would provide technical support for pre-warning monitoring and pollution control of wheat-maize rotation system.