Effect of biochar application on microbial biomass and enzymatic activities in degraded red soil

To assess biochar effect on soil microbial biomass, community and enzymatic activities, degraded acidic soil was amended with three different rates (0.5, 1.0 and 2.0%) of oak wood biochar (W0.5, W1.0 and W2.0) and bamboo biochar (B0.5, B1.0 and B2.0), with control as 0%. The soil and the biochar were mixed thoroughly, wetted and incubated at a constant temperature of 25°C. The amended soil properties were evaluated after the 1st, 8th and 16th weeks of the incubation. It was found that soil pH, total organic carbon (TOC) and urease increased significantly with increasing biochar rate while the activity of acid phosphatase decreased, the reason can be the inverse correlation of this enzyme with soil pH. TOC had positive correlation with urease. The β-glucosidase correlated positively with dissolved organic carbon (DOC) and negatively with C/N, suggesting that mineralization of organic matter provides substrates for this enzyme. The highest microbial biomass C as well as total Phospholipid fatty acid analysis (PLFA) was observed at the lowest rates, particularly the treatment of W0.5 had higher relative abundance of soil bacteria, fungi and gram-positive bacteria. Our results suggest that biochar application improve the fertility of degraded red soil by increasing soil pH, TOC and DOC which, in turn, enhance soil enzymes, microbial biomass and community.   Key words: Biochar, enzymes, microbial biomass, microbial community, phospholipid fatty acids.