Fuente: WIPO "organic farming" A method is provided for manufacturing a liquid nitrogen fertilizer from organic wastes and manures, in which nitrogen is extracted as an aqueous ammonia, and further concentrated, and eventually converted to nitrate in a biological reactor. The method may utilize nitrogen rich organic wastes and manures, such as wastewater sludge, slaughter house wastes, broiler layer, and guano, and it is especially suitable for providing a nitrogen fertilizer in organic farming.