Dual-effect alkali-modified charcoal-based vermiculite compound fertilizer for repairing heavy metal pollution of soil and regulating fertility and preparation method of dual-effect alkali-modified charcoal-based vermiculite compound fertilizer

The invention relates to the technical field of farmland soil heavy metal pollution remediation and improvement, in particular to a dual-effect alkali- modified charcoal-based vermiculite compound fertilizer for repairing heavy metal pollution of soil and regulating fertility and a preparation method of the dual-effect alkali modified charcoal-based vermiculite compound fertilizer. The compound fertilizer is prepared from the following raw materials in parts by weight: 4 parts of inorganic loading and reduction modification combined biochar and 1 part of urea, the inorganic loading and reduction modification combined biochar is prepared from inorganic loading modified biochar and a KOH solution according to the mass ratio of 1: 1, and the concentration of the KOH solution is 1 mol/L; and the inorganic loaded modified charcoal is prepared from the following raw materials in parts by weight: 5-10 parts of corn straw, 1 part of triple superphosphate and 1 part of vermiculite. A verification result shows that the