Crop residue-derived dissolved organic matter accelerates the decomposition of native soil organic carbon in a temperate agricultural ecosystem

Crop residue-derived dissolved organic matter (DOM) plays an important role in soil carbon (C) cycling. To investigate the effects of maize residue-derived DOM and urea additions on the native soil organic carbon (SOC) decomposition and soil net C balance a pot experiment was carried out during the winter wheat growing season in the North China Plain (NCP). The results showed that adding maize residue-derived DOM alone (RDOM) or together with urea (RDOM?+?N) accelerated the decomposition of native SOC and resulted in a net SOC loss. The net loss of SOC was 3.90?±?0.61 and 3.53?±?0.48?g?C?m^?2 in RDOM and RDOM?+?N treatments, respectively. The stimulatory effect of per unit DOM-C addition on the native SOC decomposition was 0.25?±?0.05 and 0.45?±?0.07 for the RDOM and RDOM?+?N treatments, respectively. Increases in the microbial biomass and the activity of β-glucosidase, invertase and cellobiohydrolase as well as soil mineral N content were responsible for a more intense priming effect in DOM-amended soils. The positive relationship between primed soil C and soil available N (R?=?0.76, P?