Following the international trends great numbers of biogas plants were opened during the last few years in Hungary. However this issue presents a number of new questions, including the subsequent use of anaerobic fermentation residues. This endproduct can be applied as fertilizer. Chemical properties of digestate are correspond to the Hungaroan Regulations. Digestate contains high amount of nitrogen which is present mainly ammonium form and this form can cause root depression and lower germination rates. High ammonium and mineral salt content of digestate increased the water soluble salt content of soil. The added amount of NH4-N transformed to NO3-N while disengage hidrogen ions from the bond. This process caused the decreasing pH. Humus content determination did not show changes. Long term experiments are needed to recognise detail effects.