Preceding crops changed greenhouse gases emission and carbon neutrality under maize-rice and double rice cropping systems

Conversion from double rice cropping (RR) to maize-rice cropping (MR) have been occurring in recent years in Asia. However, effects on the environment by introducing maize into paddy still need more examination. The objective of this study was to assess differences in greenhouse gases emissions, carbon footprint and carbon neutrality between MR and RR cropping systems from 2016 to 2018. Results showed that the global warming potential (GWP) under MR cropping was 13.0 t CO₂ eq ha⁻¹, which was 20.0% higher than that of RR (10.8 t CO₂ eq ha⁻¹) due to its higher N₂O emission. Although the GWP of MR increased, it significantly decreased carbon footprint by 17.3% in comparison with RR due to its higher gain yield. Simultaneously, MR had a substantial increase in net ecosystem economic efficiency by 62.5%. Nevertheless, carbon uptake was significantly higher in MR system, its carbon neutrality was lower than that of RR by 69.3% average. In conclusion, MR could be an effective sustainable cropping system with high yield and low carbon footprint in the subtropical regions. Considering the higher GWP of MR, further research is needed on appropriate agronomic practice to reduce carbon loss to realize higher carbon neutral potential.