Method for preparing controlled-release fertilizer from potassium feldspar

The invention discloses a method for preparing a controlled-release fertilizer from potassium feldspar, belonging to the field of controlled-release fertilizers. The controlled-release fertilizer is prepared from controlled-release particles and a coating agent, wherein the controlled-release particles are prepared from potassium nitrate, modified potassium feldspar and clay; and the coating agent is prepared from oil tea polyphenol, acrylic amide, potassium peroxodisulfate, isocyanate and the like. The method comprises the steps of mixing acrylic amide, potassium peroxodisulfate and oil tea polyphenol, reacting for a period of time by heating, cooling to the room temperature, and adding toluene diisocyanate to obtain the coating agent; and placing a granulated fertilizer into a rotary drum coating machine, spraying the coating agent on the surfaces of the particles of the fertilizer by using a spray gun, carrying out aeration drying, cooling, sieving, sealing and packaging to obtain the controlled-release fertilizer. The coating agent provided by the invention has the advantages of low cost, environment friendliness, simple preparation method and low equipment investment and is capable of easily realizing industrial production. The prepared coated controlled-release fertilizer is good in controlled-release property and simple in processing technology and can be used for crops such as flowers, fruits and vegetables and economic forests.