Rice-crayfish co-culture increases microbial necromass' contribution to the soil nitrogen pool

The rice-crayfish co-culture (RC) is a putative sustainable agricultural system. However, studies on the ecological effects of long-term RC systems were still lacking. Here, we compare enzymatic stoichiometry, microbial necromass, and microbial community between the RC and rice monoculture systems (RM). Soil enzymatic stoichiometry analysis showed that after transformation from RM to RC for about three years, ammonium nitrogen (NH4+-N) availability increased to depress relative N-acquiring enzyme production, especially for leucine aminopeptidase. The contents of microbial necromass increased approximately onefold in the RC system, making microbial necromass' contribution to the soil nitrogen (N) reach up to 46.72%. Elevation in NH4+ decreased Nacquiring enzyme, and a relatively more effective C acquisition likely benefited microbial necromass retention and production in the RC system. This study highlights that the rice-crayfish co-culture could modify the N pool of the surface paddy soil.

Automated summary

This study compared enzymatic stoichiometry, microbial necromass, and microbial community between rice-crayfish co-culture and rice monoculture systems. The results showed that after conversion to the co-culture system for about three years, the availability of ammonium nitrogen increased, leading to a decrease in relative N-acquiring enzyme production. Microbial necromass content increased approximately twofold in the co-culture system, with microbial necromass contributing up to 46.72% of soil nitrogen. The elevation in NH4+ decreased N-acquiring enzyme production, while a more effective C acquisition likely promoted microbial necromass retention and production in the co-culture system. This study highlights the modification of the N pool in the surface paddy soil by the rice-crayfish co-culture.