Community level functional diversity and enzyme activities in paddy soils under different long-term fertilizer management practices

Soil microbial community structure and function are commonly used as indicators for soil quality and fertility. The present study deals with the effect of different long-term fertilizer management practices on community-level physiological profiles (CLPP) and soil enzyme activities of paddy soils. Since 1954, chemical fertilizers have been applied in the fields as N-P2O5-K2O, and compost has been added as rice straw at 0, 7.5, 22.5, and 30.0 Mg ha(-1) in NPK, NPKC750, NPKC2250, and NPKC3000 treatments, respectively. Community-level functional diversity was significantly enhanced in the plots treated with both chemical fertilizer and compost as compared to only chemical fertilizer and untreated control plots. Average well color development (AWCD) obtained by the Biolog Eco plate indicates that there were few differences among soil samples. Shannon diversity and evenness indices were the highest in NPKC750-treated soil and the lowest in chemically fertilized soil. Dehydrogenase, cellulose, beta-glucosidase, and acid and alkaline phosphomonoesterase activities were significantly increased depending on the amount of added compost with inorganic fertilizers; the alkaline phosphomonoesterase activity was the most sensitive to treatments. Our results demonstrated that enzyme activities can be used as sensitive and liable indicators in long-term managed rice-paddy ecosystems.