Fig. 1 | Schematic representation of two mineral protection mechanisms. a, A diagram of each mechanism: surface adsorption (top panels) and pore entrapment of SOM (bottom panels) by different types of clay minerals. Litter residues are associated with clay minerals to a higher strength through surface adsorption than through pore entrapment and decomposed to different degrees by microorganisms. b, Temporal changes in the chemical composition of labile (yellow) versus recalcitrant (brown) litter residues and the compositions of microbial functional communities and necromass (blue, bacteria; red, fungi) for each mechanism.
Fig. 2 | Chemical structures and composition of litter-derived SOM. a, CP/TOSS 13C NMR spectra of maize and soya litter and their derived SOM in four model soils.b , Differences in the chemical composition of litter-derived SOM between litter and clay mineral types. Principal component analysis of the relative abundance of functional C groups determined by13C NMR among four model soils by two litter types in comparison with original maize and soya litters (top panel) and the loadings of individual functional C groups to the first two principal components (bottom panel). Open symbols are for soya litter and filled symbols for maize litte
Fig. 3 | Community compositions of microbial biomass and necromass. a, b, Microbial biomass (represented by total phospholipid fatty acids) and microbial necromass (represented by amino sugars) of different communities in model soils mixed with maize litter (left column) and soya litter (right column). Lower case letters indicate differenences in total microbial biomass or necromass among model soils for each litter type and * indicates difference between litter types for each model soil P < 0.05 (n = 3). Error bars represent standard errors (n=3).