Enhancing Simultaneous Nitrogen and Phosphorus Availability Through Biochar Addition During Chinese Medicinal Herbal Residues Composting: Synergism of Microbes and Humus

Abstract

The disposal of by-products from Chinese medicine extraction, known as Chinese medicinal herbal residues (CMHRs), is a significant environmental challenge. Aerobic composting presents a sustainable treatment method, yet optimizing nutrient transformation during this process remains a critical concern. This study investigated the impacts and mechanisms of biochar addition on the transformation of nitrogen and phosphorus, aiming to enhance the efficacy and quality of compost products. The findings revealed that incorporating biochar considerably enhanced the process of nutrient conversion. Specifically, biochar addition promoted the retention of bioavailable organic nitrogen and reduced nitrogen loss by 28.1%. Moreover, its addition inhibited the conversion of available phosphorus to non-available phosphorus but promoted its conversion to moderately available phosphorus, thus preserving phosphorus availability post-composting. Furthermore, the inclusion of biochar altered microbial community structure and fostered organic matter retention and humus formation. These changes ultimately impacted the modification of nitrogen and phosphorus forms. This research provides a viable approach and foundation for regulating the levels of nitrogen and phosphorus nutrients during composting, serving as a valuable reference for the development of sustainable utilization technologies pertaining to CMHRs.

Keywords: Biochar addition, Nitrogen transformation, Phosphorus transformation, Microbial community, Humus