Effect of long-term mineral fertilizer application on soil enzyme activities and bacterial community composition

Soil bacteria are critical to maintain soil fertility. In this study, soil chemical properties, enzyme activities and soil bacterial community from a long-term fertilizer experiment (37 years) were analysed to elaborate the effects of long-term mineral fertilizer application on soil enzyme activities and bacterial community composition. Compared with control treatment, bacterial community richness was reduced in low nitrogen (N) fertilizer and high N fertilizer treatments and increased in high N fertilizer and phosphorus (P), high N fertilizer and potassium (K) (N2K), and high N fertilizer, P and K (N2PK) treatments. The distribution of each phylum and genera was obviously changed and the range of the dominant phyla was not affected in all fertilization treatments. Principal component analysis showed that soil bacterial community in the N2K treatment was clearly different than in the N2PK treatment. The N2PK treatment had much higher available P, total organic carbon, invertase, urease and phosphatase activities than the N2K treatment, which might change soil bacterial community composition. In conclusion, fertilization with combined application of P, K and N in appropriate proportions is an optimum approach for improving soil quality and soil bacterial community abundance in non-calcareous fluro-aquic soils in the North China Plain.