Improving cropping systems reduces the carbon footprints of wheat-cotton production under different soil fertility levels

A field experiment was performed to assess the carbon footprint (CF) of four cropping systems to identify the sustainable cropping system. The four cropping systems were cotton monoculture (CM), winter wheat intercropped with cotton (WIC), wheat cropping followed by transplanted cotton (WTC) and direct-seeded cotton after winter wheat harvest (WDC). The CF calculated per unit area (CFa), yield (CFy), biomass (CFb) and economic output (CFe) increased in the order CM < WIC < WTC < WDC in the low-fertility plot and WIC < WTC < WDC < CM in the high-fertility plot. The results indicated that CM was the best cropping system in the low-fertility plot and presented CFa, CFy, CFb and CFe values of 4848.14 kg CO2eq ha−1 a−1, 0.41 kg CO2eq kg−1 a−1, 0.17 kg CO2eq kg−1 a−1 and 0.06 kg CO2eq ¥ a−1, respectively, whereas WIC was the cropping system with the lowest CFs in the high-fertility plot and presented CFa, CFy, CFb and CFe values of 14,410.70 kg CO2eq ha−1 a−1, 1.31 kg CO2eq kg−1a−1, 0.53 kg CO2eq kg−1 a−1 and 0.34 kg CO2eq ¥−1a−1, respectively. Thus, it can be concluded that improving cropping systems provides a good option for reducing CF and consequently mitigating climate change.Abbreviations: GHG: greenhouse gas; LCA: life cycle assessment; CF: carbon footprint; CFa: The CF calculated per unit area; CFy: The CF calculated per yield; CFb: The CF calculated biomass; CFe: The CF calculated per unit economic output; CM: cotton monoculture cropping system; WIC: wheat intercropped with cotton cropping; WTC: wheat cropping followed by transplanted cotton; WDC: direct-seeded cotton after wheat cropping; IPCC: Intergovernmental Panel on Climate Change; CO2eq: CO2 equivalent; SOC: soil organic carbon; PAS: publicly available specification