Soil Organic Carbon and Nitrogen Mineralization Potential of Manures Regulated by Soil Microbial Activities in Contrasting Soil Textures

Manure application and mineralization are important for soil fertility and crop productivity. This study aimed to estimate the mineralization of soil organic carbon (SOC) and nitrogen (N) following different types of manure applications in two soil textures, and to assess the response of soil microbial biomass and extracellular enzymes to SOC and N mineralization. This study involved a 100-day incubation period with the following treatments: i) no fertilization control (CK), ii) farm manure (FM), iii) poultry manure (PM), iv) sheep manure (SM), and v) compost manure (CM). Sheep manure amendment showed significantly higher SOC content and N mineralization potential in both soil textures, resulting in enhanced soil fertility and conservation of indigenous carbon. In comparison with CK, soil microbial biomass and extracellular enzyme activities were also higher in both soil textures but depicted greater microbial activities in clay loam soil than in sandy loam soil. Soil microbial biomass carbon and N, and extracellular enzymes (beta-glucosidase, chitinase, and leucine aminopeptidase) were positively correlated with SOC and N mineralization. SOC and N mineralization patterns, soil microbial biomass, and enzymes activities varied among the treatments as SM > PM > FM > CM > CK. Clay loam soil exhibited significantly higher levels of microbial activity and SOC and N mineralization than sandy loam soil, indicating a higher carbon pool and nutrient availability. These findings suggest that the mineralization patterns of different manures can be used to optimize nutrient availability in soils according to different textures.