Biochar application affects dynamics of soil microbial biomass and maize grain yield

Abstract

A pot experiment was carried out to determine effects of biochar on soil microbial biomass carbon and nitrogen during maize growing season, and grain yields were also studied after harvest. Biochar (BC) was applied at the rates of 0 (BC0), 10 (BC10), 20 (BC20), and 30 g/kg (BC30). The soil microbial biomass carbon (MBC) and nitrogen (MBN) were assessed; the maize aboveground biomass and grain yields were also evaluated. The MBC was significantly increased by 15.2%-71.8% compared with BC0 in 0-10 cm soil layer, and MBC generally increased with increasing biochar application rates compared with the control in each soil layer. Soil MBN and the ratio of MBC to MBN varied with the maize growing season. Soil MBC and MBN were relatively high at the 6-leaf stage, then decreased slowly, and remained stable across the whole growing season. No significant effect of biochar on microbial quotient was observed across growing stages. BC30 significantly increased aboveground biomass by 11.8% compared with BC0. The grain yields increased with increasing biochar rate, and the increases in BC20 and BC30 reached 11.2% and 14.1%, respectively. The application of biochar could generally increase soil microbial biomass, improving soil fertility and crop yield.