昆明松华坝水源区等高反坡阶对坡耕地土壤磷含量的影响研究

Effect of reverse-slope level terrace on the Phosphorus contents of sloping farmland in Kunming Songhuaba Reservoir

昆明松华坝水源区是水土流失重点防治区,也是面源污染来源地。针对昆明松华坝水源保护区坡耕地磷素的流失,本研究在水源区迤者小流域内坡耕地布设等高反坡阶,通过1a的野外标准径流小区定位观测,研究等高反坡阶减缓土壤磷含量流失的规律。结果表明：（1）等高反坡阶通过减少径流泥沙输出从而降低坡耕地土壤磷素的减少速率,其对地表径流的调控率在6.08%~63.35%,产沙调控率在20.10%~66.46%;（2）等高反坡阶措施具有明显的保水保土效应,使其较原状坡面全磷含量提高了22.22%,磷素含量与侵蚀量呈显著相关关系（P〈0.05）;（3）等高反坡阶处理对土壤速效磷的流失具有调控作用,雨季开始前两小区速效磷含量相差1.89%,至雨季结束速效磷含量相差33.65%,雨季结束后等高反坡阶相较于原状坡面,前者土壤速效磷含量减少率为83.26%,明显低于后者的72.27%。

For the loss of phosphorus in the sloping farmland of Kunming Songhuaba Reservoir, this research establishes an reverse-slop level terrace on the sloping farmland of small watershed of the water resource area; carries out a locating observation on the runoff plots based on the 1a outdoor standard, and conducts a comparative analysis on the soil phosphorus and the original slope. The conclusions were drawn as follows：（1） reverse-slop level terrace lowers the reduction rate of soil phosphorus of sloping farmland through reducing the output of runoff sediment. The regulating rate on surface runoff is within 6.08% ~ 63.35%, while that on the sediment yield is within 20.10% ~ 66.46%;（2） the measure of reverse-slop level terrace plays a significant role in water retention and soil conservation. In terms of phosphorus content, this measure has increased 6.95% of the content compared with that of the original slope. The phosphorus content and erosion amount is significantly correlated（P〈0.05）;（3） reverse-slop level terrace treatment contributes to the regulation of the loss of soil rapidly-available phosphorus. Before the rainy season, the content of the rapidly-available phosphorus of the two areas only differs 1.89%, and when the rainy season is over, the content differs 33.65%. After the rainy season, compared the reverse-slop level terrace to the original slope, the reduction rate of the rapidly-available phosphorus of the former soil is 72.27%; 83.26% lower than the latter significantly.