The Influence of N2O Emission to Water and Nitrogen Coupling Mechanism in Black Soil under Drip Irrigation Mode

Abstract

This experiment is aimed at revealing the main characteristics of N2O emission from soybean in black soil and clarifying the relationship between N2O emission and environmental factors; in this experiment, static chamber-gas chromatography field observation method was used; meanwhile, three different drip irrigation amounts (300 mm, 350 mm, and 400 mm) and five different nitrogen application amounts (0, 63, 72, 81, and 90 kg/hm2) were set up to study the effects of different coupling modes on soybean N2O emission and the relationship between N2O emission and environmental factors. The results showed that the peak value of N2O emission flux of soybean mainly occurred in July and August, and the amount of N2O emission flux in each growth period was flowering-podding period > branching period > seedling period > grain filling period. N2O emission increased with the increase of drip irrigation amount and nitrogen application amount. The effects of drip irrigation and nitrogen application on N2O emission were significantly different. Under the three drip irrigation modes, the N2O emission fluxes of most treatments were significantly correlated with the temperature in that day, and the soil temperature in different soil depths was significantly correlated with the N2O emission fluxes. The correlation relationship between the temperature of each soil layer under drip irrigation 300 mm and N2O emission fluxes was less than that under drip irrigation 350 mm and drip irrigation 400 mm. There was no significant correlation between N2O emission flux and NH4+-N and NO3-N, and there was no significant correlation between N2O cumulative emission and dry matter quality in the aboveground part of soybean. It shows that the emission of N2O itself is affected by multiple environmental factors and shows certain randomness. The research results can provide important theoretical basis and technical support for realizing nitrogen reduction and efficient utilization of soybean water and fertilizer in the black soil region of northeastern part of China.