Purpose <p>Biodiversity effects influence decomposition because litter types with different qualities provide disparate resources for decomposers, promoting decay through niche complementarity. Plant domestication increased litter quality and decomposability, which might alter the relationship among decomposers by reducing niche complementarity and increasing selection effects (dominance). Here, we explore the effect of domestication on these mechanisms.</p> Methods <p>We performed an incubation experiment on standardised field soil using litter mixtures of increasing levels of diversity (one, two, and four species) of eight herbaceous crops and their wild progenitors. We tested whether domestication influences biodiversity effects and the nitrogen accumulation pattern between litter types. We tested the effect of functional diversity of litter traits (Rao’s Q) on biodiversity effects of decomposition.</p> Results <p>Domestication reduced biodiversity effects during decomposition by disrupting synergistic and dominance relationships. As a result, crops lost less carbon (biomass) than expected from synergistic relationships. Nitrogen loss did not change, probably due to shifts in nitrogen transfer and release dynamics between litter types that prevented certain crops from dominating the decomposition process. Additionally, microbes from soils fed with domesticated crops incorporated less nitrogen than expected into their biomass despite the higher quality of domesticated crops.</p> Conclusion <p>Domestication reduced niche complementarity effects for carbon loss and selection effects for nitrogen loss, hinting that domestication can alter interrelated ecosystem processes differently. These effects can cascade to other trophic levels, such as soil microbes, as reflected by their reduced ability to incorporate nitrogen into their biomass in soils fed with domesticated litter mixtures.</p>