Anaerobic decomposition of plant residues from which biogas is produced, generates very large amounts of digestate. Due to its physicochemical properties post-digestion liquid can be used as a fertilizer. Postdigestion liquid was used in the field cultivation of fodder alfalfa and winter wheat. The content of macroelements and the content of protein in the grains of winter wheat fertilized with digestate were on the same levels as in the grains of wheat fertilized with mineral fertilizers. The analysis showed a similar content of macroelements in alfalfa leaves fertilized both with post-digestion liquid and mineral fertilizers as well. Fertilizing fields with digestate brings destruction of possible pathogens. Digestate utilization as a fertilizer brings tangible benefits in agricultural production, but it is also a product, the application of which can reduce the negative effects of mineral fertilization and contribute to development of sustainable agriculture. The study has shown that digestate can be used as a fertilizer.