Fig. 2

Estimated average annual greenhouse gas (GHG) emissions from synthetic N manufacture for wheat (a) and maize (b) in different agricultural regions of China (2015–2017). Error bars in the figure represent standard deviation. CF compound fertilizers, DAP diammonium phosphate, ABC ammonium bicarbonate, NEC Northeast China, NC North China, MLYR Middle and lower reaches of Yangtze River, NWC Northwest China, SSWC South and Southwest China