New insights into carbon mineralization in tropical paddy soil under land use conversion: Coupled roles of soil microbial community, metabolism, and dissolved organic matter chemodiversity

• Published in: Geoderma Vol. 432; p. 116393
• Main Authors: Wu, Dongming, Ren, Changqi, Ren, Dong, Tian, Yingjie, Li, Youping, Wu, Chunyuan, Li, Qinfen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2023
• Subjects: abandoned land; Actinobacteria; aromatic compounds; bioavailability; carbohydrates; carbon metabolism; DOM chemodiversity; eutrophication; fungi; hydrophilicity; labile carbon; land use change; Land use conversion; microbial communities; Microbial community; Microbial metabolism strategy; mineralization; paddies; paddy soils; Proteobacteria; Soil carbon mineralization; soil microorganisms; vegetables; Land use conversion; Soil carbon mineralization; Microbial community; DOM chemodiversity; Microbial metabolism strategy
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2023.116393

[Display omitted] •SOC mineralization was enhanced in abandoned land and rice-vegetable rotation.•Soil oligotrophic microbes were increased after conversion from the paddy field.•Soil nutrient supply and microbial metabolic strategy determined SOC mineralization.•Microbial metabolism was affected by DOM chemodiverstiy and microbial composition. Although the impact of land conversion on carbon mineralization in paddy soils has received increasing attention, the coupled roles of soil microdiversity and chemodiversity in these processes are largely unknown. To address this issue, the land use conversion from paddy fields (PF) to vegetable fields (VF), rice-vegetable rotation (RV), and abandoned land (AL), were investigated in this study. The relationships between soil mineralization characteristics and microbial community, metabolism physiology and dissolved organic matter (DOM) chemodiversity were analyzed. After the conversion, soil mineralization enhanced in AL and RV, which were 217.49% and 183.02% of that in PF. In contrast, no significant change was observed in VF, although the anaerobic environment was transformed into an aerobic one and the fungal richness/ diversity increased in the soil. This was because soil mineralization was directly regulated by DOM quantity and microbial metabolism of labile carbon, and indirectly by DOM chemodiversity and microbial community. Specifically, the largest mineralization in AL was attributed to the strongest microbial metabolism of labile carbon, as AL had the largest DOC contents, hydrophilic substances (e.g., carboxyl, carbohydrate, and amino), and abundant eutrophic taxa (e.g., Actinobacteria and Proteobacteria). In contrast, no significant change in VF was mainly related to more condensed aromatics and oligotrophic microbes, and fewer DOC in soil, resulting in the dominance of microbial metabolism of soil recalcitrant carbon. The recalcitrant carbon metabolism also prevailed in RV. However, RV showed moderate soil mineralization due to having the proper DOM with high bioavailability. Collectively, the results provide molecular insights into the impact of land conversion on soil mineralization from a micro-chemodiversity perspective, which highlights the importance of nutrient supply and microbial metabolism strategy.