Starch-based anti-floating hydrogel slow-release controlled-release fertilizer and preparation method thereof

The invention discloses a starch-based anti-floating hydrogel slow-release controlled-release fertilizer and a preparation method thereof. The preparation method comprises the following steps: heating starch and a cationic compound to react to obtain cationic starch; polymerizing acrylic acid through an initiator to obtain polyacrylic acid, and adding an anionic surfactant to react to obtain modified polyacrylic acid; finally, the cationic starch is prepared into cationic starch liquid; the preparation method comprises the following steps: preheating a to-be-coated fertilizer, adding microcrystalline wax, uniformly mixing, adding cationic starch liquid under rapid rotation, uniformly mixing, spraying modified polyacrylic acid, and drying to obtain the starch-based anti-floating hydrogel slow-release controlled-release fertilizer. The starch-based hydrogel controlled-release fertilizer is prepared through physical crosslinking of cationic starch and anionic polyacrylic acid, the controlled-release fertilizer c