Remediation of soil degradation in urban parks using comprehensive hydrophyte composting with microbial agents

The utilization of hydrophyte residues for in situ composting offers a potential solution to address soil degradation in urban parks. However, there is limited understanding of how long‐term in situ composting of hydrophytes impacts soil properties and microbial communities in degraded soils. This study examines the combined effects of hydrophyte compost and microbial agents on soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), cation exchange capacity (CEC), plant growth, and microbial communities in degraded soils. Hydrophytes, primarily Ceratophyllum demersum L., were harvested, dried, crushed, and directly incorporated into the soil. A microbial agent containing Bacillus subtilis and Trichoderma harzianum was applied, and two plant species, Potentilla reptans L. and Carex giraldiana Kük., were cultivated in the plots. Commercial compost served as the point of comparison. The results revealed that the application of in situ hydrophyte composting combined with microbial agents significantly enhanced plant growth. SOM, TN, TP, and CEC were notably increased, while soil pH decreased slightly. Furthermore, the structure and diversity of both bacterial and fungal communities were substantially improved. These findings demonstrate that hydrophyte composting enriches nutrient content, provides prolonged nutrient release, and improves soil and microbial community structures, thereby creating favorable conditions for groundcover plant growth. In conclusion, the integration of in situ hydrophyte composting with microbial agents presents a practical and effective strategy for soil remediation and the restoration of degraded urban park vegetation.