Effects of Biochar Amendment on Soil Microbial Biomass Carbon, Nitrogen and Dissolved Organic Carbon, Nitrogen in Paddy Soils

Biochar can influence soil microbial biomass. It is not clear how biochar amendment affects soil microbial biomass carbon and nitrogen (MBC and MBN) and dissolved organic carbon and nitrogen (DOC and DON) in double-cropping rice soils. To address this problem, two subtropical double-cropping rice soils (S1 and S2) were selected for an incubation experiment. S1 is developed from granite-weathered red soil and S2 is developed from Quaternary red clay. The following three wheat straw-derived biochar application rates were used, without N fertilizer, in each paddy soil: 0%, 1%, and 2% of soil weight, represented by CK, LB, and HB, respectively. After a 70 d incubation, soil mean MBC was 877.03 mg•kg-1, 832.11 mg•kg-1, and 849.30 mg•kg-1 in S1 for the three application rates, and 902.94 mg•kg-1, 874.19 mg•kg-1, and 883.22 mg•kg-1, respectively, in S2. S1+LB, S1+HB, and S2+LB treatments reduced soil mean MBC compared to the CK treatment (P © 2019, Science Press. All right reserved.