Effects of Long-Term Chemical Fertilization on Soil Microbial Biomass, Activity and Community in Paddy Soil in Red Soil Region of China

Effects of long-term chemical fertilization on soil microbial biomass, activity and community of the paddy soils were studied by a long-term fertilization experiment setup in 1981. The experiment has 9 treatments, i.e. CK (no fertilization), N, P, K, NP, NK, NPK (different combination of N, P, and K), 2NPK (double NPK application rate) and NPKOM (NPK plus organic manure). Results showed that fertilizer application increased soil microbial biomass, and led to diversion of soil microbial community as compared with CK. Both the soil microbial biomass and microbial activity increased in Treatment NPKOM due to the increase in soil organic matter and total nitrogen. However, the soil microbial biomass and activity were depressed in Treatment NPK, balanced fertilization, as compared with other chemical fertilization treatments (NP, NK, N, P and K). The ergosterol data showed that the proportion of fungi in soil microbial community was increased in Treatments K and NK. The results suggested that chemical fertilization may increase soil microbial properties through changing the carbon input.