红壤小流域不同土地利用方式下土壤N,P流失特征研究

Characteristics of Nitrogen and Phosphorus Loss under Different Land Use Patterns in Small Red Soil Watershed During Course of Rain

研究了次降雨过程中红壤小流域5种不同土地利用方式土壤N,P养分流失特征。结果表明,在降雨后,花生地、花-橘间作、橘园、板栗园和水田5种利用方式表层土壤N,P养分含量均有不同程度下降,其中花生地N,P含量下降最为明显,水田N,P含量降幅则最小;不同形态养分平均降幅依次为有效氮(5.49%)、有效磷(5.25%)、全氮(1.45%)、全磷(0.59%)。各样地地表径流中水溶态N,P养分含量花生地明显高于其他样地,而泥沙中N,P养分含量则以水田最高;各样地侵蚀泥沙中N,P养分有明显的富集现象,板栗园和橘园N,P养分富集率高于其他样地,水田N,P养分富集率最低。不同形态养分富集率也不同,全氮平均富集率为1.30,有效氮1.18,全磷1.11,有效磷1.38。侵蚀径流中N,P养分与表层土壤相同形态养分之间呈显著正相关。

The characteristics of nitrogen （N） and phosphorus （P） loss under 5 land use patterns were studied in Sunjia small red soil watershed during the Course of rain. The results showed that the N,P contents of the surface soil had declined in all studied land： peanut land, orange land, peanut-orange land, Chinese chestnut land and paddy field, and the declined rate were different in 5 lands use patterns, among which the decline of the N,P contents in peanut land was most obvious, while paddy field lowest, The average decline degrees of contents of different forms of nitrogen and phosphorus arrange： available nitrogen（5.49%）〉 available phosphorus（5.25%）〉total nitrogen （1.45 %）〉total phosphorus（0. 59% ）, The contents of nitrogen and phosphorus in soluble form of peanut land in runoff were obviously highest, while the contents of nitrogen and phosphorus in sedimentary form of paddy field were highest, Nitrogen and phosphorus enrichment occurred in each land use patterns, and the enrichment ratios in Chinese chestnut land and orange land were highest, while paddy field lowest. The enrichment ratios of forms of nitrogen and phosphorus were different with available nitrogen （1.18）, available phosphorus （1.38）, total nitrogen （1.30） and total phosphorus （1.11）. The contents of lost nitrogen and phosphorus in sediment were correlated positively obviously with the contents of nitrogen and phosphorus in surface soil. The AN and AP were more liable to loss than TN and TP in peanut land, orange land, peanut-orange land, Chinese chestnut land and paddy field. The contents of soluble N, P and particulate N, P in runoff were higher in initial stage than later stage. Nutrient enrichment occurred in all land use patterns, but the enrichment ratio was different： TN was 1. 11～1, 47, AN was 1. 05～1. 36, TP was 1.02～1.26 and AP was 1.12～1. 59, The enrichment ratio of N, P in sediment of Chincse chestnut land and orange land were higher than that of other lands respectively, The direct correlations among nutrients in runoff were close.