Concurrent Response of Greenhouse Soil NO3- Concentration and N2O Emissions to Nitrogen and Irrigation Management in China: A Meta-Analysis

The soil NO3- concentration and N2O emissions plays a crucial role in mitigating greenhouse gas emissions and minimizing greenhouse soil degradation concurrently. However, it is essential to understand the extent to which management practices and environmental factors influence the reduction in NO3- concentration and N2O emissions in greenhouse soils. Here, we conducted a meta-analysis, compiling a database of NO3- concentration and N2O emissions in response to either nitrogen or irrigation management in greenhouse vegetable-based systems in China. In summary, controlling the amount of total nitrogen application and irrigation water within specific ranges can effectively reduce both the greenhouse NO3- concentration and N2O emissions. Compared to chemical nitrogen management, the application of slow-release fertilizer could concurrently reduce the soil NO3- concentration and N2O emissions by 0.20 and 0.36 times, respectively. Positive relationships were observed between soil NO3- concentration and N2O emissions under conditions of higher soil organic carbon (OC), total nitrogen (TN), alkali-hydrolyzed nitrogen (AN), and pH, as well as a lower soil temperature (ST) and bulk weight (BW). Under conditions with a higher OC and pH, an appropriate nitrogen application rate is more effective in reducing N2O emissions. While increasing irrigation can reduce soil NO3- concentrations, it also raises the risk of significant NO3- leaching. Overall, nitrogen and irrigation management should be tailored to local soil physicochemical properties to concurrently regulate soil NO3- concentrations and N2O emissions in greenhouse environments.