Soil Microbial Biomass and pH as Affected by the Addition of Plant Residues

The soil microbial biomass is involved in the decomposition of organic materials and thus, the cycling of nutrients in soils. Reductions in the size and activity of the microbial biomass are frequently used as an early indicator of changes in soil chemical and physical properties resulting from management and environmental stresses in agricultural ecosystems. In a laboratory-incubated soil, we found a strong relationship between microbial biomass C and microbial biomass N. Irrespective of the type of plant residues added, soil pH was significantly correlated with microbial biomass C and microbial biomass N. Different C/N ratio of the residues was the main characteristic that affected soil microbial biomass C, N and soil pH. Microbes played a main role in plant residues decomposition and indirectly influenced of soil pH.