Fertilizer synergist containing alginate oligosaccharide as well as preparation method and application of fertilizer synergist

The invention discloses a fertilizer synergist containing alginate oligosaccharide, and belongs to the technical field of fertilizer preparation, and the synergist is added into a fertilizer, so that plants can be induced to generate disease resistance, harmful substances in soil are degraded, auxin secretion is stimulated, metabolism of the plants is accelerated, and the disease resistance of the plants is improved; the microbial agent is a mixture prepared from the following raw materials in parts by weight: 12-18 parts of alginate oligosaccharide, 18-24 parts of brevibacillus laterosporus, 5-9 parts of penicillium baylii, 7-11 parts of streptomyces rochei and 8-12 parts of trichoderma harzianum. The invention further discloses a preparation method and application of the alginate oligosaccharide-containing fertilizer synergist, the alginate oligosaccharide-containing fertilizer synergist with high purity can be prepared by utilizing the preparation method, and the performance of a fertilizer can be improved