Spatial Heterogeneity of Greenhouse Gas Emission from Cereal Crop Production Driven by Energy-Land-Water Nexus in China

Abstract Agricultural cereal production plays a crucial role feeding the world’s growing population, particularly pertaining to rice, wheat, and maize. Cereal production requires vast amounts of land and enormous energy and water resources, potentially leading to greenhouse gas (GHG) emissions. However, very little information exists on GHG emissions resulting from interactions among the land, energy, and water nexus during cereal production. To address this knowledge gap, we introduce a state-of-the-art polyphasic approach that combines national-scale survey data with statistics and emission factor data. We also investigate spatial GHG distributions of the land, energy, and water nexus involved in Chinese cereal production including rice, wheat and maize, while recommending a potential, comprehensive mitigation strategy. Results showed that total GHG emissions from these three cereal crops reached 505.5 Tg CO2eq. (i.e., land=247.5 Tg CO2eq., energy=222.1 Tg CO2eq., and water=35.9 Tg CO2eq.). The main GHG sources derived from land (through CH4 and N2O emissions) and energy consumption during N fertilizer production (i.e., GHG emissions), accounting for 55.8% and 30.5% of total GHG emissions, respectively. Additionally, GHG emissions from cereal production in Jiangxi, Henan, Anhui, and Jiangsu provinces showed large-scale spatial heterogeneity at a provincial scale due to differences in crop type, natural resources, and managerial practices. Furthermore, we found that provincial GHG emission intensity (i.e., the GHG emission per kg of crop nitrogen (N) content) varied for both different crop types and the same crop type, mainly pertaining to southern and southeastern provinces. This could be associated with the higher GHG emission and the lower N content of these regions compared to wheat and maize production regions. Finally, we propose that the collective adoption of green technologies (e.g., comprehensive mitigation and optimal crop pattern practices) and reasonable food trading practices could potentially reduce GHG emissions from the cereal production supply chain, further promoting low-carbon agricultural development and achieving the carbon neutrality of agriculture.