The invention is directed to methods for producing a granular 
nitrogen fertilizer from an organic material comprising adding a metallic salt to said organic material to form a 
slurry. Preferably the organic material comprises dewatered 
biosolids and contains water from a 
scrubber. Metallic salts that can be used comprise a salt of iron, 
zinc, or a mixture thereof. Preferred 
iron salts comprises 
ferric sulfate or 
ferric oxide, and preferred 
zinc salts comprises 
zinc sulfate or zinc 
oxide. Preferably, the metallic salt is mixed with an acid such as 
sulfuric acid to form an acidified 
metal salt. 
Slurry pH ranges from approximately 2-2.5. The acidified 
metal salt is added to the organic material in sufficient quantity to lower 
viscosity of the 
slurry such that the resulting fluid does not hinder fluid flow during operation. When the metallic salt comprises acidified 
ferric sulfate or 
ferrous sulfate, sufficient iron can be present to produce a 
fertilizer product with 0.1 weight percent to 10 weight percent 
iron sulfate calculated on a 
dry weight basis. The invention is also directed to 
fertilizer products made by the methods of the invention. Preferred products are granules and the metallic salt increases product 
hardness. 
Fertilizer granules preferably contain 
metal that is bioavailable to a 
plant when used as a fertilizer. 
Solubility of the metal of the product in water is enhanced, and the product is low 
staining.