Maize-potato residue mixing in agricultural soils enhances residue decomposition and stable carbon content by modifying the potential keystone microbial taxa
Ding Wang, Yanli Zhou, Ping Zhao, Linkang Chen, Rui Xiang, Yuji Jiang, Guangqiang Long
Abstract
Microbe-regulated organic residue decomposition is a central hub of carbon (C) cycling in ecosystems. However, little is known about the changes in organic C composition and its microbial mechanisms during mixed crop residue decomposition in agroecosystems. We conducted a field litterbag experiment to explore the changes in organic C chemical structure and their associations with microbial communities during mixed (1:1 maize:potato residues based on dry matter mass) and single-species residue decomposition in agricultural soils. Compared with single-species residues, mixed residues exhibited a positive non-additive effect, specifically higher mass loss, and more recalcitrant organic C composition. Structural equation modelling combined with network analysis suggested that residues mixing modified bacterial keystone taxa, augmented the activity of C-degrading enzymes such as β-glucosidase, and increased stable C content during mixed residues decomposition. Thus, this study highlights the potential advantages of applying residue mixtures to agri-cropping soils to increase the relative amount of persistent aromatic compounds derived from their decomposition and the importance of bacterial keystone taxa during residue decomposition.