Xinyu Zhao

The transformation of organic solid waste resource disposal into compost is in alignment with the principles of sustainable development, enhancing the recycling rate and facilitating the attainment of the dual-carbon goal. However, constrained by a disregard for other functions of compost, and the specific requirements of the soil, current compost standards continue to facilitate the development of unrestrained industries with a sole focus on high organic matter content. Therefore, refining the rough classification and single compost standard into tailored composting and fertilization protocols is necessary to meet the specific requirements of the soil. This review begins by examining the interrelationship among compost, soil, and agricultural crops by exploring the practical application and development of compost in agricultural settings. The study critically evaluates the deficiencies in the existing compost standards, focusing on raw material selection, preparation techniques, application methodologies, risk assessment, and management oversight.

The dual environmental challenges of karst areas lie in organic solid waste’s (OSW) massive generation scale and diffuse dispersion, which accelerate bedrock exposure and soil contamination, while simultaneously representing an underutilized resource for soil amendments through optimized composting. Bio-enhanced composting of multi-source OSW yields compounds with dual redox/adsorption capabilities, effectively improving soil quality and restoring ecological balance. The recycling and circular utilization of OSW resources become particularly critical in karst regions with vulnerable soil ecosystems, where sustainable resource management is urgently needed to maintain ecological balance. This review elucidates the ecological impacts of multi-source OSW compost applications on soil environments in ecologically fragile karst regions, specifically elucidating the mechanisms of heavy metals (HMs) migration–transformation and organic contaminant degradation (with emphasis on emerging pollutants), and the functional role of microbial carbon pumps in these processes. Furthermore, establishing a sustainable “multi-source OSW−compost−organic matter (adsorption and redox sites)−microorganisms−pollution remediation” cycle creates a green, low-carbon microenvironment for long-term soil remediation. Finally, this study evaluates the application prospects of the refined composting technology utilizing multi-objective regulation for OSW resource recycling and utilization in karst areas. This review provides critical insights for optimizing soil remediation strategies in karst ecosystems through organic waste valorization.