A method for producing a
poultry litter-based
fertilizer by a) supplying
poultry litter to a rotating rotary drum, b) adding acid or a source of acid to the rotating rotary drum, wherein acid reacts with the
poultry litter to form an acidified mixture, c) adding
ammonia or a source of
ammonia to the rotating rotary drum, d)
drying and cooling the ammoniated product by
evaporation of water to form a dried, cooled product in a free-flowing semi-
solid or
solid form, repeating the steps b) through d) until a desired
nitrogen content is reached in the poultry
litter-based
fertilizer.