TECHNOLOGY FOCUS - AGRICULTURE - Preferred Composition: The composite fertilizer comprises (in parts weight) phosphogypsum (3-33), long-term efficiency nitrogenous fertilizer (25-40), phosphate fertilizer (5-25), potash fertilizer (5-35) and trace elements (1-5). The composite fertilizer comprises potassium mineral powder (3-15), potassium nitrate (3-5), potassium chloride (0-94), and potassium carbonate (0-94). The trace elements comprise zinc sulfate, borax and ammonium molybdate. Preferred Compound: The phosphogypsum is industrial residue discharged by wet-process phosphoric acid device. The long-term efficiency nitrogenous fertilizer is mixed nitrogenous fertilizer containing dicyandiamide (0.1-5%), or mixture of ammonium bicarbonate containing dicyandiamide and urea (0.1-5%). The phosphate fertilizer is mixture of ammonium phosphate and diammonium phosphate. Preferred Property: The content of ammonium phosphate is 50-80 wt.% with respect to mixture of ammonium phosphate and diammonium phosphate. Preferred Process: The mixed nitrogenous fertilizer is dissolved into water, and is added with an aqueous solution for condensation and recrystallized to obtain multivariate eutectic adduct. The composite fertilizer is obtained by preparing phosphogypsum by parching phosphogypsum to form phosphogypsum with moisture content of 8% or less, crushing and filtering phosphogypsum with sieve of 20 meshes, preparing long-term efficiency nitrogenous fertilizer by dissolving component of long-term efficiency nitrogenous fertilizer in water after computation for preparing material, or condensing and crystallizing mixture to obtain an eutectic adduct, crushing potassium mineral powder, filtering mixture with sieve of 100 meshes, pelletizing the mixture, weighing component with respect to formulation, adding adhesive as an additive, uniformly mixing the mixture, pelletizing mixture, drying and sieving, testing and packing fertilizer and warehousing the packed fertilizer. ACTIVITY - Fertilizer.