Short-term cover crop carbon inputs to soil as affected by long-term cropping system management and soil fertility

•Inclusion of legumes in the cover crop mixtures increased total biomass.•Unrecovered root fragments-adjustment more than halved phyllo-and rhizodeposition.•Relative C phyllo-and rhizodeposition (%ClvPR) decreased with higher soil fertility.•Quantity of C phyllo- and rhizodeposition (qClvPR) was on average 54 kg C ha−1.•%ClvPR was the most important factor to predict qClvPR compared to plant biomass.