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(P2O 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. © 2021, Editorial Board of China Environmental Science. All right reserved.