Examination of earthworm abundance; biomass andcorrelations of soil organic matter in an irrigated (with river and catfish effluent water) and mulched agroforestry system

The aim of our study was to evaluate a complex agroforestry system with the intercropping of aerobic rice and the utilization of reclaimed water for sustainability and climate change adaptation. The foreseeable positive outcomes of the intercropping system could be higher yields for the arable crops, additional woody products and indirectly favourable microclimate, water conservation, increased biodiversity and wind damage reduction. In this study, a special rice-energy willow/poplar agroforestry system was used to analyze the effects of reused water irrigation and mulching on soil salinity, earthworm biomass and abundance, soil organic matter (SOM) content and weed coverage in treerow-dependent habitats. After a three-year irrigation period, we investigated the woody line (WL), the buffer zone (BZ) and the crop line (CL) habitats. In our small-scale (0.3 ha) experiment, aerobic rice production took place between poplar and willow rows. The rice cultivar and woody lines were irrigated with different doses of river water and effluent water from an intensive catfish farm. The effect of irrigation and organic mulching on earthworm abundance, biomass and species composition was also investigated. In conclusion, this study demonstrated the beneficial effects of straw mulching on reducing soil salinity and improving soil health indicators. Based on our results, significantly greater earthworm abundance (274 ind m−2) and earthworm biomass (54.0 g m−2) values were measured in WL than in BZ or CL habitats. There was no significant difference in weed coverage between the CL (0.61%) and BZ (1.91%), but weeds were significantly denser on the WL (12.3%). These findings emphasize the potential advantages of reused water irrigation, mulching, and agroforestry systems in promoting soil health and effective weed control. Further research is warranted to explore the long-term effects and scalability of these practices. Agroforestry systems have the potential to enhance soil biodiversity and microbial activity, which play crucial roles in nutrient cycling and soil health. By studying the effects of agroforestry practices on soil biology, we can provide valuable insights into the mechanisms underlying soil quality enhancement in these systems.