Interrelated impacts of water recirculation on soil physicochemical characteristics and bacterial co-occurrence networks: Consequences for yield sustainability in rice-crab systems

To elucidate the impact of recycled-water irrigation on agricultural systems in arid regions, we analysed the characteristics of soil-microbe interactions under two distinct irrigation methods: a fishpond-rice-crab circular water supply system (RS) and direct Yellow River irrigation (CK). The results revealed a distinct dual effect of RS on the soil microenvironment: RS significantly enhanced soil organic matter (+24.2%, P < 0.05) and salt accumulation (+25.7%–30.2%), establishing a stable environment characterised by high fertility and elevated salinity. RS enhanced assembly resilience by maintaining a somewhat greater influence of stochastic processes (MST), community assembly analysis indicated that deterministic processes (DBR) diminished with crop development in both modes. Communities may be less influenced by local environmental fluctuations due to this dynamic of active dispersal, which could facilitate microecosystem assembly in deviating from rigid environmental restrictions and progressing toward more flexible organization. Microbial diversity and community structure collaboratively enhance network stability (explained variance = 51.8%), while structural equation modelling (SEM) indicated that RS reconfigured physicochemical regulatory circuits. The dissemination of environmental disturbances was efficiently constrained under RS by a highly modular network architecture. Microecological equilibrium, maintained by significant stochasticity and functional redundancy, enabled synergistic production increases in crab (+17.15%) and rice (+2.06%) despite persistent salinity stress. The findings collectively indicate that circular irrigation functions as a bio-enhancement framework that optimises the adaptability of microecological systems, thereby boosting agricultural resilience. They also theoretically advocate for the sustainable utilisation of saline-alkaline agricultural areas in dry regions.