Litter functional dissimilarity accelerates carbon and nitrogen release from the decomposition of straw but not root in maize/legume intercropping

The decomposition of shoot and root litter has been extensively studied in natural ecosystems. Our understanding of the decomposition of plant litter including carbon (C) and nitrogen (N) release from root residues is still limited in intercropping. We addressed how C and N release from straw and root decomposition might be affected in maize/legume intercrops.

A decomposition experiment was conducted within a field experiment including two N rates (i.e. no-N and N-addition), three monocultures (maize, soybean, and peanut), and two intercrops (maize/soybean and maize/peanut). Following five retrievals of polyethylene litterbag in 341 days, we assessed the C and N loss (i.e. release) and the mixing effects of both straw and root residues.

Straws released 38.32% more C and 43.59% more N than root residues across all crop species. Maize/peanut residues showed faster C and N release than maize/soybean residues. The release of C and N was asynchronous in both straw and root decomposition in maize/peanut intercropping. Straw mixtures of maize and legume released C faster than expected from monoculture straw. Litter functional (i.e. initial chemical traits) dissimilarity between maize and legume accelerated C and N release from the decomposition of straw, but not root, in maize/legume intercropping.

These results suggest that C and N release from maize/legume residues can be explained by both residue quality and litter functional dissimilarity. Our findings have important implications for the management of straw and root residues to reduce reliance on chemical fertilizers in intercropping.