Effect of bagasse biochar on soil organic carbon fixation in manganese pollution sugarcane fields

Abstract

In order to study the mechanism of soil organic carbon transformation and fixation in manganese-contaminated farmland, 100-day indoor constant temperature incubation experiments were conducted to analyze the characteristics of soil physical and chemical properties, organic carbon mineralization, organic carbon components and enzyme activities by applying different proportions (0%, 0.5%, 2%, 5%) of biochar. The results showed that the cumulative CO2 emission decreased by 15.78~36.87% compared with the control when different proportions of biochar were applied in the manganese-contaminated soil. The cumulative CO2 emissions were reduced by 35.29~57.29% compared with the control when different proportions of biochar were applied to the uncontaminated sugarcane field soil. The microbial carbon content of uncontaminated sugarcane soil was 28.49 mg·kg-1(0.5%),37.92 mg·kg-1(2%) and 39.42 mg·kg-1(5%), respectively, which were higher than that of manganese contaminated sugarcane soil 12.72 mg·kg-1 (0.5%),13.71 mg·kg-1(2%) and 15.10 mg·kg-1 (5%). The catalase activities of manganese-contaminated sugarcane soil were 0.13 mg·g-1·min-1 (0.5%), 0.21 mg·g-1·min-1 (2%) and 0.27 mg·g-1·min-1 (5%), respectively, which were lower than those of uncontaminated sugarcane soil 9.41 mg·g-1·min-1 (0.5%), 10.01 mg·g-1·min-1 (2%), 10.91 mg·g-1·min-1(5%). The results showed that compared with uncontaminated sugarcane field soil, the application of biochar in manganese-contaminated sugarcane soil had little effect on microbial biomass carbon content and catalase activity. The application of exogenous biochar had an auxiliary effect on carbon sequestration in manganese-contaminated soil, and the application of 5% biochar had the best carbon sequestration effect.