不同施肥条件下紫色土坡耕地径流中氮素的浓度特征

Characteristics of Nitrogen Concentration in Runoff of Purple Soil Slope Farmland under Different Fertilization Conditions

在紫色土丘陵区坡耕地养分循环长期定位试验样地对2016年4次典型降雨产流进行检测,研究了常规氮磷钾肥(NPK)、秸秆还田配施氮磷钾肥(RSDNPK)、猪厩肥配施氮磷钾肥(OMNPK)、硝化抑制剂与无机氮磷钾肥混施(DCDNPK)、对照(不施肥,CK)等5个不同处理条件下氮素随径流流失特征。结果表明,在大暴雨条件下,RSDNPK施肥方式下地表径流的氮浓度最高,但在壤中流的氮浓度较低。在大雨和小雨条件下,RSDNPK施肥方式在地表径流和壤中流的氮浓度都相对较低。由于紫色土坡耕地氮素淋失机制已较为清楚,随壤中流迁移是紫色土坡耕地氮素淋失的重要机制,因此在同等降雨条件下秸秆还田施肥方式能够减少氮流失。

Four typical rainfall runoff yields in 2016 are detected by long-term positioning test plots of nutrient cycling of slope farmland in purple soil hilly region and the characteristics of nitrogen runoff loss are studied under five different treatment conditions,including no fertilization(CK),organic fertilizer(OMNPK),chemical fertilizer(NPK),straw returning to field(RSDNPK)and digestion inhibitor(DCDNPK).The results show that straw returning to field(RSDNPK)fertilization under the condition of heavy rainstorm has the highest nitrogen concentration in the surface runoff but the lowest nitrogen concentration in the subsurface runoff;straw returning to field(RSDNPK)fertilization under the conditions of heavy rain and light rain has a relatively low nitrogen concentration in both surface runoff and subsurface runoff.As the mechanism of nitrogen leaching loss from purple soil slope farmland has been relatively clear and its important mechanism is the migration with subsurface runoff,straw returning to field(RSDNPK)fertilization is capable of reducing nitrogen loss under the same rainfall condition.