Controllable biodegradable large-particle fertilizer base material as well as preparation method and application thereof

The invention discloses a controllable biodegradable large-particle fertilizer base material, and belongs to the technical field of materials and fertilizers. The base material comprises the following components in parts by weight: 28-63 parts of starch, 7-35 parts of polyvinyl alcohol, 0-7 parts of metal salt, 14-26 parts of citric acid, 1-3 parts of sodium hydroxide, 15-30 parts of glycerol and 0-10 parts of deionized water. The preparation method of the base material comprises the following technical steps: (1) preparing citric acid starch ester; (2) mixing citric acid starch ester/polyvinyl alcohol and metal salt; and (3) extrusion molding. By adjusting the ratio of the starch to the polyvinyl alcohol and chelating and bridging the starch and the polyvinyl alcohol through metal ions of the metal salt, the hydrophobic property and the mechanical property of the base material can be changed, so that the base material has the characteristic of controllable microbial degradation, and therefore, the base mater