Manure-derived Organic Matter Dynamics and Environmental Risks: A Review

Manure fertilization plays a critical role in improving soil health by supplying essential nutrients and enhancing soil organic matter (SOM), thereby influencing soil structure and biological activity. However, the effects of manure application are highly dependent on application rate, timing, and frequency, and are constrained by non-linear nutrient dynamics and potential environmental risks. This review synthesizes field-based evidence to evaluate the impacts of manure-derived organic matter on soil physicochemical properties, microbial processes, and environmental risks. Repeated manure applications gradually increase SOM, thereby improving aggregate stability through microbial activity, pore structure, and reduced bulk density, aiding infiltration and nutrient transport. Furthermore, SOM leads to greater microbial biomass, a more diverse community structure, and higher enzyme activity. However, these benefits are accompanied by environmental risks, including phosphorus (P) accumulation, nitrate (NO3−) leaching, greenhouse gas emissions, heavy metal buildup, and the proliferation of antibiotic resistance. Evidence further indicates that short-term improvements may mask long-term constraints driven by nutrient saturation and contaminant accumulation. Integrated nutrient management strategies are therefore essential to balance agronomic benefits with environmental risks. While manure application can improve crop yield and grain nutritional quality, its economic and environmental performance remains context-dependent. Overall, manure should be considered as a valuable but management-intensive resource for sustainable agriculture. • Manure-derived organic matter controls multiple soil functions simultaneously. • Repeated manure application creates cumulative environmental trade-offs. • Sustainable manure management requires balancing efficiency and risks.