Long-term sustained-release compound fertilizer with long-term ammonium chloride produced with combined-soda process as nitrogen source, and preparation method thereof

The invention relates to a long-term sustained-release compound fertilizer, and specifically relates to a long-term sustained-release compound fertilizer with a nitrogen source of a by-product ammonium chloride which is obtained in a process for producing soda ash with a combined-soda process, and a preparation method thereof. In the compound fertilizer, the weight ratio of effective components is that nitrogen (N): phosphorus (P2O5): potassium (K2O) =10-15:8-12:8-15, and a total nutrient content is 30-42. The nitrogen is obtained by mixing ammonium chloride and an ammonium stabilizer. According to the weight, ammonium chloride: the ammonium stabilizer=1:0.001-0.1, wherein the ammonium chloride is a by-product ammonium chloride obtained in a process for producing soda ash with a combined-soda process. The long-term sustained-release compound fertilizer provided by the invention has the advantages of long-lasting effect and precise sustained-release agent target. The effectiveness of the composite fertilizer is improved, wherein nitrogen utilization rate of ammonium chloride is improved by 10-20 percentage points, and ammonium chloride utilization amount is reduced by 20-50%.