Effects of bio-compound fertilizer on soil microbial communityfunctional diversity and microbial biomass

The characteristics of soil microbes are sensitive indicators for soil fertility. Fertilization could influence soil physiochemical and biological properties. This study illustrated the functions of bio-compound fertilizers in maintaining good soil micro-ecological environment using the Biolog ECO micro-plate technique and CHCl3 fumigation-extraction method. The study investigated the effects of bio-compound fertilizer, organic-inorganic compound fertilizer and inorganic fertilizer at equal N, P and K amounts on functional diversities of soil microbial communities and microbial biomass under short-term potted corn experiment in greenhouse conditions. The six types of substances that composed Biolog ECO plate substrates included carbohydrates, carboxylic acids, amino acids, polymers, amines and aromatic chemicals. Principal Component Analysis (PCA) depicted different utilization forms of resource carbon by soil microbes. Average well-color development (AWCD), Shannon index (H) and richness index (S) of soil microbe communities were the highest in bio-compound fertilizer treatment. Bio-compound fertilizers obviously increased microbial source carbon utility, especially those of aromatic chemicals and carbohydrates. A significant difference existed in metabolic ability of soil microorganisms under different fertilizer treatments. Bio-compound fertilizer score was positive for the first principal component, while other treatments scores were negative. The determinant carbon sources for the differences were carbohydrates and carboxylic acids. During corn growth period, soil microbial biomass increased gradually and then stable with time. The amounts of soil microbial biomass C (333.21 mg?kg^-1), N (53.02 mg?kg^-1) and P (22.20 mg?kg^-1) were highest under bio-compound fertilizer treatment. At the same nutrient rates, bio-compound fertilization significantly improved utilization rates of carbon source, richness indexes and functional diversities of soil microbial community. This also increased the amounts of soil microbial biomass C, N and P.