Soil remediation agent prepared from crop straw and biochar and preparation method of soil remediation agent

The invention discloses a soil remediation agent prepared from crop straw and biochar and a preparation method of the soil remediation agent, belongs to the technical field of soil remediation, and particularly relates to a soil remediation agent prepared from modified crop straw, nano-modified biochar, a compound microbial agent, an organic material, a decomposition agent and a medium trace element solution. Heavy metal ions are strongly adsorbed by the modified crop straws and the nano-modified biochar, excessive salt in soil is neutralized and adjusted under the combined action of the modified crop straws, the organic materials and the decomposition agent, organic matters, elements necessary for plant growth and beneficial microorganisms are released, and the air permeability of the soil is improved; when the compound microbial agent is used together with the compound microbial agent, phosphorus and potassium can be dissolved, soil salt damage can be reduced, and the pH value of soil can be adjusted; meanw