Implication of Temporal Dynamics of Microbial Abundance and Nutrients to Soil Fertility under Biochar Application – Field Experiments Conducted in a Brown Soil Cultivated with Soybean, North China

Abstract

A short-term experiment was conducted to investigate responses of microbial community composition and nutrients dynamics to biochar-amended brown soil. We examined the effect of biochar on microbial abundance by plate counting method and microbial community composition changes by DGGE, as well as effect on total and available nutrients N, P and K content. Soil pH measurement was also incorporated into our study. The overall results showed that bacterial abundance increased more than actinomycetes, but fungal abundance decreased slightly in biochar amended soil in later sampling times. In terms of microbial community composition, DGGE analysis for bacteria exhibited some specific lanes in biochar treatments. Bacterial community was more sensitive to sampling time, but fungal community was influenced greatly by biochar addition. In our study, total C content increased significantly, as biochar rate and sampling time preceded. Total N increased slightly in later sampling time, and thus C and N ratio increase was obtained. Total P and K changes were not obvious. Extractable N and pH increased. Microbial utilization was assumed to contribute to extractable P and K decrease in later sampling times. Results suggested that biochar incorporation to brown soil might bring potential benefit to soil fertility from N retention in soil. Microbial turnover may feedback P and K to soil as well in the long term. There may also be an implication of beneficial effect on disease alleviation lead by microbial community imbalance.