To burn or retain crop residues on croplands? An integrated analysis of crop residue management in China

Crop residue burning influences human health and global climate change. In China-the world's largest crop residue producer-farmers burn almost one quarter of their crop residues in the field after harvest, despite the government providing financial incentives such as subsidies to retain crop residues. This study combined economic analyses with simulations of soil carbon accumulation and carbon emission reduction associated with different residue management practices to determine the minimum level of incentives needed for Chinese farmers to shift from burning to retaining crop residues for generating carbon benefits. Simulation results showed that [1] the density of topsoil organic carbon in China's croplands would have increased from about 21.8 t ha(-1) in 2000 to 23.9 t ha(-1) in 2010, and soil organic carbon sequestration would have reached 24.4 Tg C yr(-1) if farmers had shifted from burning to retaining crop residues on croplands during this period; and [2] retaining crop residues would have avoided about 149.9 Tg of CO2 emission per year. Economic analyses showed that [1] existing subsidies in all regions of China, except Northeast China, only accounted for 18-82% of the incentives required for farmers to shift from burning to crop residue retention; [2] Northeast China required the lowest incentive (287 CNY ha(-1)), while eastern China required the highest (837 CNY ha(-1)); and [3] the prevailing market prices (1.4-60.2 CNY tCO(2)e(-1)) in China's seven pilot carbon markets seem to be below the required incentives (39.6-189.1 CNY tCO(2)e(-1)). Our study suggests that the Chinese government should increase subsidies or seek innovative incentive schemes to encourage farmers to change their crop residue management practices for global climate change mitigation and health benefits. (C) 2019 Published by Elsevier B.V.