Soil texture and straw type modulate the chemical structure of residues during four-year decomposition by regulating bacterial and fungal communities

Authors: LI, DANDAN - Chinese Academy Of Sciences; ZHAO, BINGZI - Chinese Academy Of Sciences; Olk, Daniel - Dan; ZHANG, JIABAO - Chinese Academy Of Sciences

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2020
Publication Date: 5/28/2020
Citation: Li, D., Zhao, B., Olk, D.C., Zhang, J. 2020. Soil texture and straw type modulate the chemical structure of residues during four-year decomposition by regulating bacterial and fungal communities. Applied Soil Ecology. 155. Article 103664. https://doi.org/10.1016/j.apsoil.2020.103664.
DOI: https://doi.org/10.1016/j.apsoil.2020.103664

Interpretive Summary: Soil organic matter plays central roles in multiple soil processes, but the factors of its formation and composition remain controversial. For example, it is unclear whether different crops will alter the formation of soil organic matter. In this study we measured the chemical composition and dominant microbial communities of corn and wheat straws that were decomposed during four-year incubation in three soils that varied in texture. We found that in the sandy soil, the chemical compositions of both straw types following decomposition were similar, as were their dominant microbial populations. But for two finer-textured soils the corn straw provided for different chemical compositions and microbial communities in both soils than did the wheat straw. These results indicate that straw type and soil conditions can all influence the formation of new soil organic matter. These results will help soil scientists better understand the formation of new soil organic matter and thus improve our ability to manage its activity in several soil processes. The results will benefit soil science researchers, especially soil organic matter specialists and soil microbiologists.

Technical Abstract: The manners of changes in chemical structure and microbial decomposer communities during straw degradation have been inconsistent in previous reports, showing both convergence or divergence of chemical structures and microbial communities among different straw types. Hence, the strength of the relationship between straw chemical composition and microbial communities remains unclear. Here, we directly measured for wheat (Triticum sp.) and maize (Zea mays L.) residues their chemical structures by 13C nuclear magnetic resonance spectroscopy and also their bacterial and fungal communities after four-year decomposition in three Calcaric Fluvisols that varied in soil texture. The types of chemical alterations in straw residues that occurred during decomposition were generally coupled with trends in the communities of bacterial and fungal decomposers, but the nature of their coupling varied with soil texture. In a sandy soil, the overall soil condition promoted the same few bacterial and fungal communities for both straw types, driving in turn the convergence of chemical structures that developed during decomposition of both straws. In the sandy loam and silty clay soils, by contrast, straw type was the primary regulator of the colonizing bacterial and fungal communities, which resulted in the divergence of chemical structures between corn and wheat straw. Our results help resolve previously reported inconsistencies in the formation and stabilization of straw-derived soil organic matter in different soil conditions.