Red mud-based geological fertilizer as well as preparation method and application thereof

The invention provides a red-mud-based geological fertilizer which is prepared by taking activated red mud and an organic material as main raw materials, adding water, uniformly mixing to form a mixture, and then carrying out corrosion, matrix prefabrication, composting reaction, drying, crushing and sieving, the mass ratio of the activated red mud in the mixture is 10%-30%, the mass ratio of the added water is 45%-55%, and the balance is the organic material; the actually measured C/N of the organic material is 25-35; the preparation method of the red-mud-based geological fertilizer comprises the following steps: decay reaction, matrix prefabrication, composting reaction, drying, crushing and sieving. The red-mud-based geological fertilizer is applied to the aspect of rocky desertification soil improvement. The red-mud-based geological fertilizer prepared by adopting the technical scheme is a porous red-mud-based structural material, the conversion and fixation rate of nutrient elements such as carbon and ni