紫色土小流域种植模式对土壤氮素流失的影响初探

Effects of Planting Pattern on N Loss by Runoff in Purple Soil Agro-watersheds

种植模式变化是农业非点源污染流域治理最佳管理措施的主要内容之一,以紫色土区徐家湾和桑树土典型农业小流域为例,初步探讨了套种和单作模式下自然降雨侵蚀过程次降雨土壤氮素的流失特征。结果表明,土壤硝态氮流失表现为套种与单作模式下的差异不显著,而铵态氮的流失受流域种植模式变化的影响强烈,套种模式下的平均流失浓度(0.453mg/L)明显大于单种模式下的(0.169mg/L)。套种模式应与流域土壤-作物系统的科学管理有机结合才能在提高土地生产力的同时有效地减控流域土壤氮素的非点源流失。

Agricultural non-point source pollution could be reduced and controlled by alternative of planting pattern, and thus it is considered one of best management practices （BMPs）. Xu jian-wan and Sang shu-tu agro-watersheds were taken examples to investigate the effects of inter-planting and monocuhure on nitrogen loss by runoff under the erosion of natural rainfalls in purple soil region. Results showed that the response of soil nitrate loss by runoff was insensitive to the altering of planting pattern, while that of soil ammonium was very sensitive. It was found that the average concentration of soil ammonium loss under the pattern of inter-planting （0.453 my/L） was significantly higher than that of under the monocuhure （0.169 my/L）. This revealed that inter-planting pattern could effectively increase land productivity and minish the N loss by runoff when it was carried out along with scientific management of soil-crop system.