Plant litter is the main carbon (C) source of belowground communities, influencing the functioning of terrestrial ecosystems. In cultivated systems, litter varies quantitatively (restitution or exportation of aerial plant parts) and qualitatively (crop rotation) throughout the year. The effects of litter quantity and quality on the soil biota structure and their relative contributions at different trophic levels have rarely been simultaneously assessed in agricultural soils. To evaluate the role of litter quality and quantity on soil food webs, we incorporated two litter types (labile or recalcitrant) and two litter quantities (low or high) in a long-term experimental site studying the impact of different cultural practices in Northern France. After 7 months, we measured the litter mass loss, enzymatic activities (hydrolytic and oxidative), nitrogen (N) content and biomass of the soil biota: microorganisms, nematodes, Acari, Collembola, earthworms and macro-arthropods. Litter quantity and quality had distinct effects on the structure and functions of soil communities. Doubling the quantity of added litter caused deep changes in the composition of detritivorous fauna by promoting the largest-sized group of detritivores (anecic earthworms) to the detriment of the smaller-sized groups (Collembola), which in turn led to higher litter consumption for a similar amount of soil biota biomass and hydrolytic enzyme activities after seven months of decomposition. In contrast, low litter quality stimulated the fungal energy channel, with an increase in the relative proportion of fungi, fungal feeding nematodes and euedaphic and hemiedaphic collembolans. This food web was characterized by a shift towards nitrogen acquisition that decreased the C:N ratio of enzymatic activities. Litter management is a central factor to consider for influencing ecosystem services such as soil fertility and nutrient cycling through the promotion of specific functional groups in soil.