Differential effects of fresh and composted organic wastes on soil bacterial community and maize growth

The use of organic waste in agriculture improves soil health although its interaction with mineral fertilizers is not fully understood. This study investigated the impact of combining mineral fertilizers with organic wastes, such as sugarcane filter cake, poultry litter, and chicken manure in both fresh and composted forms, on maize (Zea mays) growth, soil bacterial communities, and their potential metabolic functions. The assessment was conducted 90 days post-application on two different soil types (i.e., clay and sandy clay loam) in a greenhouse setting. While fresh animal-derived organic wastes generally boost short-term plant growth and nutrient uptake, composted wastes can be more effective in reducing nitrogen losses and methane emissions over the long term. The impact of organic waste on soil microbial communities and functions varies, with fresh wastes increasing nitrification and methanogenesis, while composted wastes tend to stabilize carbon and reduce these processes. Evaluating different organic waste sources and forms, and considering their C:N ratios, is crucial for optimizing soil health and minimizing greenhouse gas emissions. They also boosted plant growth and nutrient uptake, whereas composted waste increased soil mineral-associated organic matter (a more stable carbon pool) and phosphorus availability. These findings are crucial for optimizing the synergy between organic wastes and mineral fertilizers to enhance soil productivity and agricultural sustainability.