不同灌溉方式旱田土壤N2O排放和氮素淋溶特征

通过野外原位监测试验，利用静态箱-气相色谱法、土壤溶液提取器分别对旱田土壤N₂O排放及氮素淋溶进行2018和2019年连续两年观测.试验设计为DCK （滴灌无肥）、DD （滴灌+N 500kg/hm²）、DG （滴灌+N 1000kg/hm²）、FCK （沟灌无肥）、FD （沟灌+N 500kg/hm²）、FG （沟灌+N 1000kg/hm²）.结果表明，不同施氮量、不同灌溉方式对N₂O排放和氮素淋溶量影响具有极显著差异（P<0.01）.N₂O排放量随施氮量的增加而增加，滴灌与沟灌相比可有效降低N₂O排放，2018和2019年FCK、FD、FG的N₂O累积排放量分别为2，23.79，45.73kg/hm²和2.08，6.23，13.93kg/hm²，而DCK、DD、DG分别降低了35%、80.9%、75.6%和26.7%、66.4%、21.5%.2018和2019年旱田土壤氮素淋溶量均表现为：滴灌<沟灌，80cm深度土壤溶液氮素淋溶量<40cm.2018和2019年相同施氮量下滴灌与沟灌相比，在40cm和80cm分别能减少氮素淋溶量36.95%~63.10%和54.93%~87.92%.主成分分析结果表明，影响N₂O排放的主要环境因子为土壤NO₃^--N含量和降水频率，相关系数分别为0.689、0.596；影响氮素淋溶量的主要环境因子为降水频率和灌水频率，相关系数分别为0.697和-0.729.滴灌可有效减少N₂O排放和氮素淋溶量，在提高肥料利用率的同时可减轻环境污染.

Characteristics of N2O emissions and nitrogen leaching from upland soils under drip or furrow irrigation

In present study, a two-year experiment in the field was performed, and the static chamber and soil solution extractor were used to quantify N₂O emissions and nitrogen leaching from upland soils. The treatments include DCK(drip irrigation without fertilizer)、DD(drip irrigation +N 500kg/hm²)、DG(drip irrigation +N 1000kg/hm²)、FCK(furrow irrigation without fertilizer)、FD(furrow irrigation +N 500kg/hm²)、FG(furrow irrigation +N 1000kg/hm²).The results showed that there were significant differences in N₂O emissions and nitrogen leaching under different nitrogen fertilizer application and irrigation methods(P<0.01). N₂O emissions increased with the increase of nitrogen applications. Compared with furrow irrigation, drip irrigation effectively reduced N₂O emissions, the cumulative N₂O emissions of FCK、FD、FG were 2, 23.79, 45.73kg/hm² and 2.08, 6.23, 13.93kg/hm² in 2018 and 2019, respectively; DCK、DD、DG reduced cumulative N₂O emissions by 35%、80.9%、75.6% and 26.7%、66.4%、21.5%, respectively. Cumulative N leaching from upland soils showed that drip irrigation produced less nitrogen leaching than furrow irrigation, nitrogen leached less at the depth of 80cm that at 40cm. Compare with to furrow irrigation, drip irrigation at the depth 40cm、80cm reduced cumulative N leaching amounts (on equivalent N application amounts) by 36.95%~63.10 and 54.93%~87.92% in two years. The results of principal component analysis showed that N₂O emissions were mainly determined by soil nitrate nitrogen content and the frequency of precipitation, the correlation coefficients were 0.689 and 0.596, respectively; nitrogen leaching amounts were mainly determined by the frequency of precipitation and irrigation, the correlation coefficients were 0.697 and -0.729, respectively. Drip irrigation effectively reduced the amounts of N₂O emissions and nitrogen leaching amounts, at the same time, it could increase nitrogen utilization efficiency and decrease nitrate pollution on the environment.