有机肥对滇中红壤烤烟坡耕地氮磷流失的影响

Effects of organic fertilizer on nitrogen and phosphorus loss in flue-cured sloping farmland of red soil in central Yunnan

【目的】研究自然降雨条件下施用有机肥对滇中坡耕地产流产沙与氮磷流失特征的影响,旨在为该地区肥料合理施用及坡耕地土壤侵蚀状况改善提供科学依据。【方法】以滇中二龙潭小流域红壤烤烟坡耕地为研究对象,在施用相同化肥的基础上,设置6种有机肥用量处理,分别为0 kg/m2(CK)、0.25 kg/m2(T1)、0.50 kg/m2(T2)、0.75 kg/m2(T3)、1.00 kg/m2(T4)和1.25 kg/m2(T5),选取4场自然降雨,研究不同有机肥用量条件下坡耕地径流及其泥沙中的氮磷流失特征。【结果】(1)4场降雨条件下,不同处理的径流量和产沙量无显著差异,而降雨量和降雨强度对径流量和产沙量影响较大。(2)随着有机肥用量的增加,径流中总氮(TN)、NO3--N、NH4+-N质量浓度总体降低,表现为CK>T1>T2>T3>T4>T5;溶解态氮是径流中氮素的主要存在形式,而NO3--N又是溶解态氮的主要组成部分。(3)随着有机肥用量的增加,径流中总磷(TP)及PO43--P质量浓度明显降低,均表现为CK>T1>T2>T3>T4>T5;径流中TP、PO43--P质量浓度随着施肥时间的延长呈明显降低趋势。(4)在4场降雨过程中,泥沙中的TN和TP含量均随着有机肥用量的增加而降低。(5)有机肥用量的增加降低了坡耕地TN、TP流失总量,TN流失以径流输出为主,TP流失以泥沙输出为主。【结论】探明了自然降雨条件下施用有机肥后红壤坡耕地氮磷流失规律,为减少研究区氮磷流失量,雨季应尽量减少或避免农事活动,暴雨情况下应控制氮磷的输出,并可以通过增加有机肥用量和减少化肥用量的方式降低氮磷的输出。

【Objective】Under natural rainfall conditions,the effects of organic fertilizer application on runoff,sediment,and nitrogen and phosphorus loss in sloping farmland of central Yunnan were studied to provide basis for rational application of fertilizer and soil erosion of slope farmland.【Method】In this study,the sloping farmland of Erlongtan watershed in central Yunnan was selected for 6 different treatments of CK,T1(0.25 kg/m 2),T2(0.50 kg/m 2),T3(0.75 kg/m 2),T4(1.00 kg/m 2)and T5(1.25 kg/m 2)with same organic fertilizer.Four natural rainfalls were selected to study nitrogen and phosphorus loss and runoff and sediment characteristics under different organic fertilizer applications.【Result】(1)Under 4 rainfall conditions,there was no significant difference between runoff and sediment in different treatments,while rainfall and rainfall intensity had great impacts on runoff and sediment.(2)With the increase of organic fertilizer,the concentrations of TN,NO 3--N and NH 4+-N in runoff under different treatments decreased with the order of CK>T1>T2>T3>T4>T5.Dissolved nitrogen was the main form of nitrogen in runoff and NO 3--N was the main component of dissolved nitrogen.(3)With the increase of organic fertilizer,the concentrations of TP and PO 43--P in runoff were significantly reduced in the order of CK>T1>T2>T3>T4>T5.The concentrations of TP and PO 43--P in runoff showed a decreasing trend along time.(4)In the process of 4 rainfall events,the contents of TN and TP in sediment decreased with the increase of organic fertilizer.(5)The total losses of TN and TP in slope farmland were reduced with the increase of organic fertilizer.The main loss of total nitrogen was runoff and that of total phosphorus was sediment.【Conclusion】The agricultural activities should be reduced or avoided in rainy season to reduce nitrogen and phosphorus loss.The output of nitrogen and phosphorus should be controlled under heavy rain,and can be reduced by increasing the application of organic fertilizer and reducing the application of chemical fertilizer.