Preparation method and application of calcium peroxide composite slow-release agent

The invention provides a preparation method of a calcium peroxide composite slow-release agent. The preparation method comprises the following steps: S1, mixing polyvinyl alcohol, sodium alginate and water to prepare a mixed solution; wherein the mass ratio of the polyvinyl alcohol to the sodium alginate to the water is (2-5): 1: (30-50), and the preparation condition is that the polyvinyl alcohol, the sodium alginate and the water are stirred for 4-5 hours at the temperature of 60-80 DEG C and the speed of 80-120 rpm; s2, calcium peroxide, glucose, biochar and a pH regulator are added into the mixed solution and stirred and mixed uniformly, a mixture is obtained, the stirring time is 5-10 min, and the temperature is 2-5 DEG C; wherein the mass ratio of the calcium peroxide to the glucose to the biochar to the pH regulator is 1: (0.5-2.5): (0.1-0.2): (0.1-0.12); and S3, pouring the mixture into a mold, freezing, unfreezing, and taking out and drying after a plurality of freezing and thawing cycles. The compos