降雨对农家堆肥氮磷流失的影响及其面源污染风险分析

采用原位研究方法,经过历时120 d的农家堆肥试验,对比分析了秸秆、棚膜、土层、裸露等4种覆盖堆肥方式中,降雨对总氮、氨氮、硝态氮、总磷和可溶性磷径流流失的影响及其面源污染风险.结果表明,各种覆盖方式的堆肥随着堆肥的腐熟和径流的增加,氮素、磷素的径流流失浓度逐渐降低,其中总氮、氨氮、硝态氮浓度随时间的变化符合一级动力学方程,而总磷、可溶性磷符合直线方程.从各处理趋势来看,各种氮磷养分径流流失浓度与流失强度表现为无覆盖>秸秆覆盖>土层覆盖>棚膜覆盖.棚膜覆盖堆肥对面源污染的风险较小,可以作为改善农村环境卫生、控制氮磷流失的堆肥方法.

Effects of Rainfall on Nitrogen and Phosphorus Loss from Courtyard Compost and Its Risk of Nonpoint Source Pollution

The in situ 120 days experiment was conducted to investigate effects of rainfall on nitrogen and phosphorus loss from courtyard composting with four kinds of coverage, involving no coverage, rice straw, thin film and soil, and their risks of nonpoint source pollution were discussed. The results showed that, with decomposing of the manure and increasing of runoff, the concentration of total nitrogen (TN), ammoniac nitrogen (NH4(+)-N), nitrate nitrogen (NO3(-)-N), total phosphorus (TP) and dissolved phosphorus (DP) from courtyard composting decreased. Especially, the concentration variation of TN, NH4(+)-N, NO3(-)-N with time fit for I kinetic equation, while TP and DP fit for linear equation. The concentration order of nitrogen and phosphorus in runoff observed as follows: no coverage > coverage by rice straw > coverage by soil > coverage by thin film. As a result, the coverage by thin film could be used as a recommended mode to decrease the loss of nitrogen and phosphorus in runoff resulting from its low risks for nonpoint source pollution.