滇中红壤丘陵区不同土地利用类型坡地氮磷流失特征

为揭示红壤丘陵区不同土地利用类型坡地径流及氮磷流失特征,以滇中仓房小流域3种土地利用类型(林地、灌草地、农地)为研究对象,通过测定2018年雨季自然降雨过程中不同土地利用类型径流量、氮磷流失形态、质量浓度及流失量,研究了红壤丘陵区径流及氮磷流失特征。结果表明:(1)不同土地利用类型下径流量与降雨量和降雨强度均呈显著正相关,总径流量表现为:林地(20.12 L/m2)<灌草地(23.80 L/m2)<农地(34.34 L/m2),各土地利用类型的变异系数为0.14~0.64,差异较大;(2)自然降雨条件下TN,NO-3-N和NH+4-N质量浓度均值表现为林地(3.20,2.08,0.50 mg/L)<灌草地(4.09,2.57,0.58 mg/L)<农地(4.95,3.16,0.88 mg/L),TP和PO-4-P质量浓度均值表现为林地(3.43,1.95 mg/L)<灌草地(4.33,2.57 mg/L)<农地(5.82,3.61 mg/L);(3)溶解态氮磷是径流水体中氮磷污染的主要污染物,其中NO-3-N和PO-4-P为径流氮磷流失的主要形态(56.81%~77.41%和50.12%~76.64%);(4)不同土地利用类型下TN和TP流失总量表现为林地(59.96,65.47 mg/m2)<灌草地(98.92,102.95 mg/m2)<农地(170.28,200.94 mg/m2)。因此,通过在流域内增加林地和灌草地面积,开展退耕还林还草工程,可减少该流域氮磷流失量,从而减缓和防治云南红壤丘陵区水土流失。

Characteristics of Nitrogen and Phosphorus Losses Under Different Land-use Types in Red Soil Hilly Area in Central Yunnan Province

Three land use types(forest, shrub and farmland) in Cangfang small watershed in central Yunnan Province were studied as the research sites to reveal the characteristics of runoff and nitrogen and phosphorus losses in slope lands with different land use types in red soil hilly area. Runoff, nitrogen and phosphorus loss forms, concentrations and loss amounts of different land use types were measured during natural rainfall in rainy season in 2018. Characteristics of runoff, nitrogen and phosphorus losses in red soil hilly region were studied. The results showed that:(1) there was a significant positive correlation between runoff and rainfall and rainfall intensity under different land use types;the total runoff increased in the order: forest land(20.12 L/m2)