The effects of crop domestication on litter quality and mixing effects during decomposition differ between leaves and roots

Plant domestication influences chemical and physical characteristics of litter, which are important drivers of litter mixture decomposition and nutrient recycling in agroecosystems. Despite roots being the primary litter input in croplands, most previous studies in croplands examined leaf litter decomposition. While crop leaf litter decay has been compared to that of their wild progenitors, crop root litter decomposition has only been compared with that of their wild relatives rather than their direct wild progenitors. This bias limits our understanding of how domestication-induced changes in litter quality during crop evolution under domestication affected litter decomposition, litter mixture effects, and nutrient cycling in agroecosystems. To address this knowledge gap, we performed a laboratory decomposition assay using eight herbaceous crops and their wild progenitors. We investigated the impact of domestication on leaf and root litter traits and tested whether domestication affected the decomposability and mixing effects of leaf and root litter mixtures differently. In general, the effects of domestication on litter traits were specific to the trait, crop, and organ (leaf or root). Nonetheless, domestication tended to improve litter quality by increasing the manganese content and reducing the dry matter content. Leaf litter decomposed faster than root litter, but domestication did not affect total litter mass loss in either plant organ. However, the data showed that domestication increased mixing effects on leaf litter mixtures but not in root litter mixtures. These differences in litter traits and decomposition suggest that domestication affects nutrient cycling dynamics differently in leaf and root litter. Therefore, understanding these differences could help develop leaf and root litter amendments that promote long-term soil fertility and increase soil carbon sequestration in agroecosystems.