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

Abstract

The changes of chemical structure and decomposer community during straw degradation have been inconsistent in previous reports, showing either convergence or divergence of chemical structures or microbial communities among different straw types. Hence the strength of their relationship remains unclear. Here, we directly measured the chemical structures and bacterial and fungal communities of wheat (Triticum aestivum L.) and maize (Zea mays L.) residues after four-year decomposition in three Calcaric Fluvisols that varied in soil textures. Separation of the chemical structures among the six soil-straw combinations (two straw types × three soil textures) were generally coupled with trends in the communities of bacterial and fungal decomposers, but the nature of their coupling differed. In the sand soil, soil texture was the central feature that shaped bacterial and fungal communities for both straw types, driving in turn the convergence of chemical structures of both decomposing straws. In contrast, in the sandy loam and silty clay soils, straw type was the primary regulator of the colonizing bacterial and fungal communities, which resulted in the divergence of chemical structures according to straw type.