The invention discloses a method for reducing the
bioavailability of soil with combined heavy
metal pollution. The method comprises the following steps: subjecting the soil with combined heavy
metal pollution to
air drying, sieving and preservation; with agricultural and
forestry residues as raw materials, preparing
biochar particles, and carrying out crushing, screening,
air drying or stoving, and preservation; mixing the screened dried
biochar particles and the soil with combined heavy
metal pollution in a weight ratio of 1: 20 to 1: 100 under stirring, adding
distilled water to allow the
water content of the obtained mixture to reach 50 to 70% of field
moisture capacity, and subjecting the mixture to standing for 5 to 7 days to allow the mixture to be fully decomposed so as to prepare achar-soil mixture with combined heavy
metal pollution; and
transplanting tobacco seedlings into the
char-soil mixture by using a well cellar
seedling transplanting method, uniformly filling the wellcellar with the mixture and allowing the growing points of the tobacco seedlings to main exposed. The method provided by the invention substantially reduces the available contents of Cd and Pb in thesoil with combined heavy
metal pollution and lower absorption and enrichment of the
heavy metals Cd and Pb by the roots, stems and leaves of crops; and the method has the advantages of low cost, highefficiency, simple operation and easy promotion and application.