DMAP type slow-release fertilizer and preparation method thereof

The invention discloses a DMAP type slow-release fertilizer and a preparation method thereof. The slow-release fertilizer is prepared from the following raw materials in parts by weight: 8-10 parts of humate, 1-3 parts of gelatin, 5-8 parts of sodium alginate, 2-5 parts of starch, 10-15 parts of urea, 1-3 parts of zinc sulfate, 1-1.5 parts of manganese sulfate, 1-3 parts of ferrous sulfate, 1-1.5 parts of boric acid, 0.5-1 part of sodium molybdate, 2-3 parts of ammonium citrate, 10-15 parts of water-retaining resin and 30-40 parts of water. The main chain of the water retention resin molecule is a polyacrylic resin chain, polyacrylic resin has a good water absorption effect, in the using process of the slow release fertilizer, the fertilizer is further protected against the influence of water and soil loss, crops can make full use of nutrients, meanwhile, cellulose and chitosan serve as matrixes, and the water retention effect is good. The prepared water-retaining resin can be quickly degraded by soil after b