Reducing greenhouse gas emissions and increasing yield through manure substitution and supplemental irrigation in dryland of northwest China

Achieving carbon neutrality is a global goal, and increasing crop yield while reducing agriculture-related greenhouse gas (GHG, including CO2, CH4, and N2O) emissions is an urgent challenge. In the dryland of northwest China, the high input of nitrogen (N) fertilizer drives high GHG emissions. Replacement of part of the N fertilizer with manure (NM) and adding supplemental irrigation water (NMW) to NM can significantly increase crop yields. However, it is still unknown whether the increased yield would induce more GHG emissions. In this study, the change in GHG emissions were investigated under conventional farmer N application (FN), NM and NMW in winter wheat cropping systems. The two-year study showed that the global warming potential, greenhouse gas intensity and carbon footprint of NM and NMW were 3-25%, 21-42% and 9-18% lower, respectively, than those of FN, owing to the lower N fertilizer and the associated N2O emissions under NM and NMW. In addition, compared with FN, CO2 emissions during the growing season were higher under NM and NMW; however, due to the 23-40% higher biomass productivity, NM and NMW neutralized and fixed more CO2 (21-39% higher net ecosystem productivity) than FN. Therefore, NM and NMW could be favorable agronomic practices in the Loess Plateau when considering the dual goal of maintaining acceptable yields while reducing GHG emissions.

Automated summary

In the dryland of northwest China, replacing part of nitrogen fertilizer with manure and adding supplemental irrigation water can increase winter wheat yield while reducing greenhouse gas emissions.