Effects of rice-Cherax quadricarinatus integrated farming system on ammonia emission of rice field and nitrogen accumulation in rice

Objective To explore the impact of the rice-red claw crayfish (Cherax quadricarinatus) farming model on ammonia (NH₃) volatilization loss in paddy field and nitrogen accumulation in rice plants, and provide a theoretical basis for optimizing input management in paddy field and efficient utilization of resources.

Method Field experiments were conducted with three treatments including blank control (CK, rice monoculture without fertilizer application and crayfish introduction), conventional rice monoculture (RM), and rice-red claw crayfish farming (RN). The monitoring areas of RN treatment included the rice planting area and ditch area. The variation trend of soil NH₃ volatilization and nitrogen use efficiency of rice in different rice ecosystems were determinated.

Result The ditch area in the RN mode could effectively reduce the NH₃ volatilization flux compared to the rice planting area and the RM mode. Under higher nitrogen input conditions, the RN mode did not significantly increase the loss of NH₃ volatilization in paddy field, and the loss value showed a decreasing trend. The NH₃ volatilization flux in paddy field was significantly positively correlated with the surface water ammonium nitrogen (NH₄⁺-N) and total nitrogen (TN) concentrations (P<0.01). The RN mode increased soil nitrogen content through higher nitrogen input, and the crayfish activity improved soil aeration to promote nitrogen absorption by rice roots, thereby significantly increasing nitrogen accumulation (10.2%) in rice total plants at maturity (P<0.05).

Conclusion Compared to the RM system, the RN system has a higher nitrogen assimilation potential, which could potentially inhibit soil NH₃ volatilization, increase nitrogen absorption and accumulation of rice, and achieve higher nitrogen use efficiency.