Method for preparing special fertilizer for day-lily buds and producing byproduct sodium dihydrogen phosphate

The invention relates to the technical field of chemical industry and discloses a method for preparing a special fertilizer for day-lily buds and producing a byproduct sodium dihydrogen phosphate. The technical problems that the fertilizer applied to day-lily buds is not completely absorbed by the day-lily buds, some element compounds are remained in soil, the soil structure is changed and the environment is polluted because the nutrient element match in the conventional fertilizer does not meet the requirements of the day-lily buds on the nutrient elements are solved. The method comprises the following steps: reacting phosphoric acid and carbamide to generate an intermediate, and reacting the intermediate with an alkaline sodium salt, so that one part of sodium dihydrogen phosphate generated in the reaction is crystallized and separated out, and the content of nitrogen and phosphorus in the reaction solution is regulated to meet the needs of growth of day-lily buds; adding potassium and other medium trace element compounds into the reaction solution so as to prepare the special fertilizer for day-lily buds. The special fertilizer for day-lily buds is low in production cost, can be greatly utilized and has obvious economic values.