Soil Nitrous Oxide Emissions Under Maize-Legume Intercropping System in the North China Plain

Many studies have focused on various agricultural management measures to reduce agricultural nitrous oxide(N2O) emission. Howev er, few studies have investigated soil N2O emissions in intercropping systems in the North China Plain. Thus, we conducted a field experiment to compare N2O emissions under monoculture and maize-legume intercropping systems. In 2010, five treatments, including monocultured maize(M), maize-peanut(MP), maize-alfalfa(MA), maize-soybean(MS), and maize-sweet clover(MSC) intercropping were designed to investigate this issue using the static chamber technique. In 2011, M, MP, and MS remained, and monocultured peanuts(P) and soybean(S) were added to the trial. The results showed that total production of N2O from different treatments ranged from(0.87±0.12) to(1.17±0.11) kg ha-1 in 2010, while those ranged from(3.35±0.30) to(9.10±2.09) kg ha-1 in 2011. MA and MSC had no significant effect on soil N2O production compared to that of M(P<0.05). Cumulative N2O emissions from MP in 2010 were significantly lower than those from M, but the result was the opposite in 2011(P<0.05). MS significantly reduced soil N2O emissions by 25.55 and 48.84% in 2010 and 2011, respectively(P<0.05). Soil N2O emissions were significantly correlated with soil water content, soil temperature, nitrification potential, soil NH4+, and soil NO3- content(R2=0.160-0.764, P<0. 01). A stepwise linear regression analysis indicated that soil N2O release was mainly controlled by the interaction between soil moisture and soil NO3- content(R2=0.828, P<0.001). These results indicate that MS had a coincident effect on soil N2O flux and significantly reduced soil N2O production compared to that of M over two growing seasons.