Subsurface Drip Irrigation with Emitters Placed at Suitable Depth Can Mitigate N2O Emissions and Enhance Chinese Cabbage Yield under Greenhouse Cultivation

Abstract

Agricultural practices, such as applying excessive water and nitrogen fertilizer to increase the crop yield, can be a significant source of greenhouse gas emissions (GHGs). Therefore, techniques and proper management are needed to mitigate these emissions without yield reduction. The experiment used three subsurface drip irrigation (SDI) depths with emitters buried at 0.05, 0.10, and 0.15 m below the soil surface, along with two nitrogen fertilizer (Urea, N > 46.2%) application levels of 300 kg N ha−1 (N300) and 240 kg N ha−1 (N240) to investigate the effect of vertical and horizontal water and fertilizer distribution on N2O emissions under different SDI techniques in greenhouse conditions. The results indicated that soil N2O emissions from SDI10 and SDI15 decreased by 7.06% and 10.69%, respectively, compared to SDI5. N2O, WFPS, NH4+-N, and NO3−-N were significantly reduced with the increased radial distance from the emitter. N2O was positively correlated to WFPS and NH4+-N while negatively correlated to NO3−-N. The NH4+-N and NO3−-N concentrations decreased with depth and increased with fertilization events. Furthermore, N2O, WFPS, NH4+-N, and NO3−-N were increased under N300 compared to N240 (p > 0.05). The findings demonstrated that the Chinese cabbage yield was significantly enhanced under SDI15 compared to SDI5 and SDI10. Furthermore, N300 can increase the cabbage yield more than N240 among all treatments.