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 estimation 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 addition, the trench resulted in remarkably more CH4 emissions due to higher mcrA abundance and lower pmoA abundance 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 %.