Preparation method of soil bioremediation agent and remediation of mercury-polluted cultivated land by using soil bioremediation agent

The invention provides a method for in-situ remediation of mercury-contaminated cultivated land by using a soil bioremediation agent, and relates to remediation of mercury-contaminated soil of cultivated land. The soil bioremediation agent comprises the following raw materials: plant fibers and microorganisms, the plant fibers are one or a mixture of more of plant fibers such as barks, sawdust, soybean meal, peanut shells and rice bran, and the microorganisms are one or a mixed microorganism of bacillus subtilis and bacillus cereus. The soil bioremediation agent is prepared by fermenting the plant fibers with bacillus microorganisms under certain conditions. The soil bioremediation agent has the advantages that the preparation method of the soil bioremediation agent is simple, raw materials are natural in source, and secondary pollution to soil is avoided; (2) construction is convenient, special sowing equipment or earthwork is not needed, farmland fallow is not needed during application, and normal agricultu