Abstract:In order to investigate the effect of biochar on dissolved organic matter (DOM) in soil, the anaerobic mud culture experiment of adding biochar to paddy soil was carried out to analyze the dissolved organic carbon (DOC) content, the composition of DOM, the fluorescence spectrum characteristics and the Fe (Ⅲ) reduction in anaerobic mud during different culture stages after adding biochar. The results showed that the addition of biochar could increase the content of DOC in paddy soil and impact the ultraviolet spectrum characteristic value (SUVA254), resulting in the changes of the component and the relative content of DOM, and the changes among different soils were different, the role of biochar was more obvious in acid paddy soil. The reduction efficiency of Fe (Ⅲ) was promoted by adding biochar, and the initial soil pH was also impacted. The correlation analysis revealed that the addition of biochar could affect the nitrate reduction, iron reduction and methanogenesis in anaerobic paddy soils by adjusting SUVA254, DOM composition and pH of the incubation system.