Integrated rice-crayfish farming system does not mitigate the global warming potential during rice season

Integrated rice-crayfish farming system (RCS) has become increasingly popular in China. However, previous research has largely ignored the effect of trench around the paddy field on GHG emissions, which may cause inaccurate estima-tion of the global warming potential (GWP) from the system. This study compared the GWP between rice monoculture (RM) and RCS. The results indicated that the field of RCS had significantly lower CH4 emissions compared with RM due to lower mcrA abundance and higher pmoA abundance, while there was no difference in N2O emissions. In addi-tion, the trench resulted in remarkably more CH4 emissions due to higher mcrA abundance and lower pmoA abun-dance and less N2O emissions than the field in RCS. In general, RCS seems not to mitigate GWP compared with RM due to more CH4 emissions from the trench in the current mode. Furthermore, our results indicate that RCS can reduce GWP relative to RM only when the area ratio of the trench to the system is controlled to be lower than 13.9 %.

Automated summary

Integrated rice-crayfish farming system (RCS) is popular in China, but the impact of trench on greenhouse gas (GHG) emissions has been ignored. This study compared GHG emissions between rice monoculture (RM) and RCS, finding that RCS had lower CH4 emissions due to lower mcrA abundance and higher pmoA abundance. However, the trench resulted in higher CH4 emissions and lower N2O emissions compared to the RCS field. Overall, RCS does not mitigate global warming potential (GWP) compared to RM, unless the area ratio of the trench to the system is controlled below 13.9%.