三峡库区坡耕地氮磷径流特征

Run-off Character of Nitrogen and Phosphorus on Slope Land in Three Gorges Reservoir

在三峡库区不同土壤类型(石灰土、紫色土)、坡度(5°、15°、25°)、种植模式(柑桔-牧草、蔬菜-马铃薯、玉米-小麦))上建立径流小区,旨在研究自然环境条件下土壤氮磷径流特点。结果表明不同条件下的土壤参数(pH、有机质、全氮、碱解氮、全磷、有效磷)、径流水参数(pH、总氮、总磷)、流失泥沙参数(pH、有机质、全氮、碱解氮、全磷、有效磷)的含量差异较大,各参数间的相关性差异也较大。径流水的pH和总磷在石灰土和紫色土间达显著性差异,紫色土径流水总磷浓度的变化幅度和平均值均大于石灰土。紫色土径流水pH同总氮协同作用明显,同总磷拮抗作用明显。土壤有机质同径流水和流失泥沙中多个参数间有直线关系,控制土壤氮、磷输入能防止水体酸化的危险。氮径流率平均值为紫色土>石灰土,磷径流率平均值为石灰土>紫色土。土壤氮平均流失量在15°坡度时最大(1.428 kg hm-2),土壤磷平均流失量在25°坡度时最大(0.565kg hm-2)。4个月(5～8月)库区坡耕地土壤氮和磷平均流失量分别为1.038 kg hm-2、0.509 kg hm-2。

The experiment was conducted to investigate the run-off characteristics of soil nitrogen and phosphorus in different types of soil（lime soil and purple soil） and slopes（5°,15° and 25°） and plantation patterns（orange-weed,vegetable-potato and corn-wheat） under nature condition.The results showed great variations among the parameters of soil（pH,organic matter,total nitrogen,alkali nitrogen,total phosphorus and effective phosphorus）,run-off water（pH,total nitrogen and total phosphorus）,and the lost sediment（pH,organic matter,total nitrogen,alkali nitrogen,total phosphorus and effective phosphorus）.The correlations among the above parameters also changed greatly.The pH values and total phosphorus contents in the run-off water were significantly different between purple soil and lime soil.The variation scopes and average concentrations of total phosphorus in the runoff water of purple soil were greater than those of lime soil.As for the run-off water in purple soil,the pH was significantly synergistic with total nitrogen while antagonistic to total phosphorus.There were straight line relationships between soil organic matter and many parameters of run-off water and the lost sediment.Controlling the inputs of nitrogen and phosphorus into soil could prevent acidification of water.Average run-off ratio of nitrogen in purple soil was bigger than that in lime soil,but the trend of run-off ratio for phosphorus was reverse.When the slope was 15°,the average run-off nitrogen content of soil was biggest（1.428 kg hm-2）;when the slope was 25°,the average run-off phosphorus content was biggest（0.565 kg hm-2）.In four months（May to August） from slope land in Three Gorges Reservoir,average amounts of run-off nitrogen and phosphorus in soil were 1.038 kg hm-2 and 0.509 kg hm-2,respectively.