Effect of 25-year fertilization on soil microbial biomass and community structure in a continuous corn cropping system

A split-plot trial with three replicas in Northeast China was carried out to investigate the effects of 25-year corn stalk (CS) and mineral fertilizer application on soil microbial biomass and the microbial community structure in a continuous corn cropping system. The main plots were treated with CS including 0 (CS0), 2500 (CS1), and 5000 (CS2) kgha(-1). Subplots were split into N (N), NP (NP), nitrogen, phosphorus, and potassium (NPK), and non-fertilizer control (O). The results showed that N application (CS0N) decreased soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen, bacterial phospholipid-derived fatty acids (PLFAs), and fungal PLFAs compared with the treatments of O, NP, and NPK with CS0. Compared with CS0, CS application (CS1 and CS2) increased SMBC, total PLFAs, Gram(+) PLFAs, and Gram(-) PLFAs. CS of 5000kgha(-1) combined with NPK application (CS2NPK) had the highest SMBC, soil microbial biomass nitrogen, total PLFAs, and bacterial PLFAs. Principal component analysis demonstrated that CS application had distinct effects on soil microbial community structure relative to the non-CS application. Our results provide a better understanding of the significance of corn stalk-balanced fertilization with NPK in promoting the soil microbial biomass and the microbial community structure in the continuous corn cropping system.