单次和间歇性降雨下紫色土坡地壤中硝氮迁移特征

为探究不同降雨条件下不同观测时期硝氮在紫色土坡地中的迁移特征,通过室内土槽和人工模拟降雨装置,设置单次降雨和间歇性多次(12次)降雨条件,分别探讨短时期和长时期下的紫色土壤中硝氮迁移特征.结果 表明:在单次降雨后短期内紫色土坡地距地表15 cm处土壤水和硝氮均匀地向下距地表35 cm土壤坡脚处迁移,而在间歇性12次降雨...

Characteristics of Nitrate Nitrogen Transport of Purple Sloped Soils in Response to Single and Intermittent Rainfalls

To investigate characteristics of nitrate nitrogen transport in purple sloped soils at different periods under different rainfall events, laboratory soil tanks and simulated rainfall installation were equipped to set each single and total 12 intermittent rainfalls, and nitrate transport characteristics during short and long time periods were discussed respectively. In each soil tank, eight observed points were designed uniformly along the soil profile. The results showed that the soil water and nitrate nitrogen of purple sloped soils transported evenly from the upper 15 cm depth soil layer to the foot slope of lower 35 cm depth soil layer. However, nitrate concentrations of observed points declined rapidly from initial 345.7 mg/L to 99.7 mg/L during the first 6 rainfall events of 12 intermittent rainfalls; mean nitrate concentrations decreased from 69.7 mg/L to 52.0 mg/L during the 7^th to 9^th rainfall event, and tended to stable. As rainfall occurred, nitrate nitrogen transported towards the lower and foot of sloped soils, and the top of slope showed minimal transport. In addition, the nitrate concentration of subsurface outflow was about 1/3 of that of subsurface soil water. Overall, subsurface nitrate loss showed rapid decrease after 3 rainfall events. This research provided better understanding for nitrate transport and loss mechanism of purple sloped farmland as response to intermittent rainfall events, which was from a bran-new perspective.