Compound fertilizer for increasing porosity of soil and preparation method thereof

The invention discloses a compound fertilizer capable of increasing soil porosity and a preparation method thereof, and solves the technical problem that in the prior art, waste fly ash is not used for preparing a compound fertilizer which can well prevent soil hardening, improve soil air permeability and enhance soil fertilizer and water permeation. The fertilizer comprises the following components in percentage by mass: 40-60% of fly ash, 10-25% of desulfurized gypsum, 30-50% of air-dried cow dung, 5% of phosphate-solubilizing bacterial liquid and 5% of potassium-releasing bacterial liquid. The fly ash is adopted to prepare the compound fertilizer, solid waste is consumed, meanwhile, the soil structure can be effectively improved, soil hardening is broken, and the soil porosity is increased; meanwhile, Si, Ca, S, Fe, Mg and the like in the fly ash are well utilized by the compound fertilizer, wherein the elements belong to citric acid soluble and soluble elements and can be directly absorbed and utilized by