Assessment of greenhouse gases emissions, global warming potential and net ecosystem economic benefits from wheat field with reduced irrigation and nitrogen management in an arid region of China

In the context of global warming, water scarcity, and high fertilizer costs, identifying proper irrigation and nitrogen (N) management is essential for balancing emissions of greenhouse gases (GHGs), crop production, and economic benefits in arid regions. A two-year field study was conducted to determine the interactive effects of irrigation regimes (I100, 750 mm; I80, 600 mm and I60, 450 mm) and N application rates (N100, 300 kg ha-1; N75, 225 kg ha-1; and N50, 150 kg ha-1) on GHGs emissions, global warming potential (GWP), greenhouse gas intensity (GHGI), and net ecosystem economic benefits (NEEB) from spring wheat field in Northwest China. Our results depicted the lowest cumulative GHGs emissions and GWP with low irrigation and low N application rates but at the cost of a significant decrease in grain yield and NEEB compared to full irrigation and N application. Instead, moderate irrigation and N application (I80N75) showed the most promising effects by significantly reducing GHGs emissions while improving the NEEB and yield benefits. Compared to I100N100, the I80N75 treatment decreased cumulative N2O emissions by 43.2 % and 33.1 %, CO2 by 28.8 % and 26.2 %, GWP by 46.8 % and 35.6 %, and GHGI by 55.0 % and 43.5 % in 2015 and 2016, respectively. In addition, the I80N75 treatment improved the NEEB by 79.3 % and 78.6 % and grain yield by 15.2 % and 16.1 % in 2015 and 2016 compared to I100N100, respectively. The wheat field acted as a CH4 sink regardless of all the treatments. Soil moisture and inorganic N contents were the primary driving factors that influenced the GHGs emissions from the wheat field, manifested by their significant correlations. Overall, 600 mm irrigation and 225 kg N ha-1 fertilization is an effective strategy with a good trade-off between economic benefits and environmental performance from spring wheat fields in the arid region of Northwest China.