The invention discloses a method for producing
nitrogen-fixing
potassium slow-release compound
fertilizer with mesh inner membranes by using an
ammonia-acid method. The compound
fertilizer comprises the following added raw materials: natural minerals capable of fixing and absorbing nutrients, and raw materials capable of forming shells with porous multiple
layers of mesh inner membranes; and
calcium salt is used to form a packaging skeleton and fix nutrients. The added concentrated
sulfuric acid is divided into two parts, wherein one part is prepared into an
ammonium sulfate solution of 180-220 DEG C with
ammonia and water,
amino acid reaction heat is controlled through controlling the added amount of water, and then the
ammonium sulfate solution is sprayed into a granulator to granulate with powdery basic materials which contain
nitrogen,
phosphorus,
potassium and natural minerals and are capable of forming shells with mesh inner membranes; and the other part is diluted and then directly added into the granulator to react with
urea to generate thiocarbamide, and then
drying, cooling, screening and enveloping are carried out on thiocarbamide after granulating to obtain the slow-release compound
fertilizer containing
nitrogen,
phosphorus and
potassium. In addition, two-section
drying is changed to one-section
drying, which can meet the requirements of production.