丹江口库区坡耕地柑橘园套种绿肥对氮磷径流流失的影响

Effects of Green Manure Planting on Nitrogen and Phosphorus Losses Along with Runoff from Citrus Orchards on Sloping Land in the Danjiangkou Reservoir Area

采用野外天然降雨条件下的径流小区试验,研究了丹江口库区坡地果园套种三叶草(Trifolium repens)、黑麦草(Lolium perenne L.)、苕子(Vicia villosa Roth)绿肥作物对氮磷径流流失的影响。结果表明:果园套种绿肥作物三叶草、黑麦草、苕子径流水量流失分别减少24.7%,31.6%和13.9%,泥沙流失分别减少36.4%,29.6%和15.7%,土壤保水能力和固土能力加强。地表径流是果园氮磷养分流失的主要途径,种植绿肥作物三叶草、黑麦草、苕子能使总氮流失分别减少30.5%,20.6%和23.9%,总磷流失分别减少52.8%,33.3%和42.3%。对不同处理地表径流水体氮素形态特征分析表明,可溶性氮素占总氮的比例较高,可溶性氮素中以硝态氮为主,铵态氮所占比重较低。坡地果园套种绿肥可使氮磷流失量明显降低,有助于水体环境的保护,同时还可改善果实品质。试验结果对库区面源污染的控制,重点水源地的水质保护提供了借鉴。

The effect of nitrogen and phosphorus runoff loss was studied in a mountainous orchard by covering planting green manure experiment in natural rainfall condition.The result showed that mountainous orchard by covering planting green manure Trifolium repens,Lolium perenne and Vicia villosa could decrease the water runoff loss by 24.7%,31.6% and 13.9%,respectively;the amount soil erosion loss decreased by 36.4%,29.6% and 15.7%,respectively,so covering planting green manure in the mountainous orchard was a good technology to reduce water runoff loss and soil erosion.The nitrogen and phosphorus in the runoff water were the main types of soil nutrient losses in the mountainous orchard.The total nitrogen loss decreased by 30.5%,20.6% and 23.9%,and phosphorus loss was decreased by 52.8%,33.3% and 42.3%,respectively,with covering planting green manure.Much more nitrogen was lost than phosphorus from mountainous orchard soil,and the soluble nitrogen accounted for much of total nitrogen loss,primarily in the nitrate form rather than the ammonium form.It was conclude that covering planting green manure was a good way to decrease the nutrient loss es along with runoff and protect the water environment,and at the same time it was beneficial for improving the fruit quality.These results suggest that covering planting green manure is effective to control agricultural non-point source pollution in the Danjiangkou Reservoir area.