The present invention relates to a method for producing an organic fertilizer with humic substance properties by oxidizing and ammonifying lignite, wherein the organic fertilizer has a nitrogen content of up to 8 wt. %, based on the dry weight of the fertilizer, and a C/N ratio of 7 to 15, which is characterized in that the method is carried out as a continuous method and comprises the following steps: a) dispersing the lignite and aqueous ammonia solution in a dispersing circuit having a dispersing device, a recirculation container, and a recirculation pump; b) oxidizing the suspension from step a) with an oxygen-containing oxidizing agent at a temperature of 50° C.; and d) cooling the dried product obtained in step c).