Double-film double-control composite synergistic fertilizer and preparation method thereof

The invention provides a double-film double-control type composite synergistic fertilizer and a preparation method thereof, the double-film double-control type composite synergistic fertilizer contains a slow-release fertilizer, the slow-release fertilizer adopts a seaweed film as a coating material, alginic acid is added into the inclusion of the slow-release fertilizer, and the content of the slow-release fertilizer is added into the seaweed film. Another slow-release fertilizer adopts polyurethane or other inorganic matters as a coating material. The double-film double-control composite synergistic fertilizer disclosed by the invention not only comprises a slow-release fertilizer which adopts the seaweed film as a coating material and contains alginic acid, but also comprises a slow-release fertilizer which adopts polyurethane or other inorganic matters as a coating material. The value-added effect of alginic acid and the long-acting effect of polyurethane coated urea are fully exerted, and the composite t