Preparation of avermectin slag fertilizer

The invention relates to a preparation method of abamectin dreg fertilizer; the method solves the problem that: the existing preparation method of the organic fertilizer affects the content of total nitrogen, total phosphorus and total potassium when reducing the content of inorganic nitrogen, phosphorus and potassium in the fertilizer. The preparation method is characterized in that: the preparation method comprises the following steps: (1) dairy manure, slag, maize straw, ammonium hydrogen carbonate and potassium sulphate are uniformly mixed, composted and fermented; after the fermentation is finished, the dairy manure, the inorganic nutrients of which are fixed by microorganisms is obtained; (2) the abamectin dreg is dried to have 40-55% of the water content; (3) the dairy manure, the inorganic nutrients of which are fixed by microorganisms, the abamectin dreg, humic acid and argil are uniformly mixed and are made into particles, thus obtaining the abamectin dreg fertilizer. The method not only can improve the content of total nitrogen, total phosphorus and total potassium in the organic fertilizer, but also can effectively reduce the content of inorganic nitrogen, phosphorus and potassium in the fertilizer simultaneously; therefore, the produced fertilizer has high content of the total nitrogen, the total phosphorus, the total potassium and organic matters.