鄱阳湖区坡耕地水土流失对土壤养分的影响

Effect of Soil and Water Erosion on Soil Nutrients on the Slope Farmland in Poyang Lake Region

通过在鄱阳湖区坡典型耕地上设置横坡垄作、顺坡垄作、植物篱+顺坡垄作、裸露对照等水土保持措施的试验观测小区,收集降雨时的径流与泥沙,分析水土流失对氮、磷、有机质等土壤养分流失的影响。径流中流失的氮以可溶性有机氮为主(60%),在有效氮中又以氨态氮为主(90%以上),泥沙中的氮流失以有机态为主(90%),泥沙中磷的流失主要是无效磷;土壤氮、磷、有机质的流失主要以泥沙携带为主,氮、磷、有机质的流失量均与土壤侵蚀量、径流深等呈0.05水平的极显著正相关;在不同水土保持措施下,氮、磷和有机质的流失均表现为横坡垄作<顺坡垄作+植物篱<顺坡垄作<裸地,说明在坡耕地中水土保持措施、特别是减少泥沙流失的措施对保护土壤养分效果明显。

Based on the arrangement of 12 experiment plots including 4 types of soil and water conserva-tion measures which were the cross ridge , down slope tillage , down slope tillage ＋living hedgerow and bare land,and the data of the runoff and sediment during raining ,the effect of soil and water erosion on loss of soil nutrient including nitrogen ,phosphorus and organic matter was analyzed .The result showed that nitrogen loss in runoff was mainly soluble organic nitrogen （ 60%） , the main loss in available nitrogen was ammonia nitrogen （ more than 90%） ,nitrogen loss in sediment was mainly of organic form （ 90%） ,main phosphorus loss in the sediment was ineffective phosphorus;the losses of soil nitrogen ,phosphorus ,organic matter were mainly in the sediment carriage ,all the correlations of nitrogen loss , phosphorus loss , organic matter loss with soil erosion , runoff depth were extremely significant ,at the level of 0.05;with different soil and water conservation measures ,nitrogen,phosphorus and organic matter losses showed the order of cross ridge ＆lt;down slope tillage＆lt;down slope tillage＋living hedgerow＆lt;bare land ,which indicated that soil and water conservation measures on the slope farm -land has obvious effect on reducing the soil nutrients loss ,especially the measures for reduction of sediment .