In the European Union, the agricultural sector is responsible for more than 10% of greenhouse gas emissions; however, unlike other sectors, agriculture has huge potential in terms of sequestering atmospheric CO₂ given the possibility of storing it in organic form in the soil. The use of cover crops in crop rotation contributes to the sustainability of the agroecosystem with regard to the maintenance of biodiversity and the possibility of less fertilizer use. Our research was set up in 2022 at the University of Debrecen Research Institute of Nyíregyháza, Hungary, in humic–sandy soil. We evaluated the biomass-producing capacity and forecrop value of five cover crop mixtures and three single cover crop species in terms of the corn yield over two crop seasons. The treatments were compared with fertilized (80 kg ha^-1 N) and control treatments. The cover crop species were common vetch, oil radish, and buckwheat, and the mixtures included melioration radish, field pea, black oats, phacelia, and crimson clover. The mixture of common vetch and oil radish produced the highest above-ground fresh biomass (56.47 and 64.50 t ha^-1) in both of the investigated years. In 2023, the most successful treatments in terms of corn yield were the cover crop mixtures that included a cruciferous species or phacelia in addition to a leguminous component. In these cases, the corn yields (13.52 – 13.83 t ha^-1) significantly exceeded the yield of the control treatment (9.45 t ha^-1) and were equivalent to those under the fertilizer treatment (11.71 t ha^-1). In 2024, no significant differences were detected in terms of the corn yield; however, the results of the fertilized treatment (9.72 t ha^-1) were exceeded by those using the application of the common vetch cover crop (10.72 t ha^-1). Based on our results, the application of leguminous cover crops and their mixtures contributes to sustainable corn cultivation.