天然降雨下红壤坡地氮磷流失过程与特征分析

Processes and Characteristics of Nitrogen and Phosphorus Losses on Red-soil Sloping Land Under Natural Rainfall

利用江西省水土保持生态科技园的野外实测资料,对天然降雨条件下南方红壤区自然坡面的氮磷流失过程与特征进行了分析。结果表明,在自然条件下,由于降雨强度的时间变化不稳定,且不连续,自然坡面产流—产沙过程也是不稳定和不连续的,呈现出一峰或多峰的特性;同一场降雨下自然坡面的产沙过程与产流过程基本一致,累积产沙量和累积径流量随时间的延长呈现出先小幅增长后快速增加,最后趋于平稳的变化趋势。坡面径流中总磷的输出浓度始终小于总氮输出浓度,且总磷变化稳定,总氮波动较大;侵蚀泥沙中均存在养分富集现象,且总氮富集比要小于总磷富集比。

In order to study nitrogen and phosphorus losses on red-soil sloping land,field experiments under three typical natural rain events were performed to investigate the N and P transferring processes and their characteristics in the SWC Ecological Science and Technology Demonstration Park of Jiangxi Province.Results showed that under the condition of natural rainfall,the processes of runoff and sediment on natural slope were not stable and continuous and had one or more peak values,because rainfall intensity was not stable and continuous.The processes of runoff and sediment on natural slope were basically the same for the same rainfall event.The cumulative sediment yield and cumulative runoff with time showed a slight growth and then a rapid growth,and tend to change smoothly.The concentration of phosphorus was lower than that of nitrogen,and changes in P concentration were more stable than those in N concentration.There were nutrition enrichments in eroded sediment,and the N enrichment ratio was lower than the P enrichment ratio under the three rain events.