To accomplish soil recycling through such a process that, ordinary soft soil, in particular silt- or sludge-like soil containing toxic heavy metals, organomercuric compounds, halogens and halides, and ordinary soil contaminated with toxic substances, or the like, are made to promote their decomposition and/or segregation reaction using a specific chemical solvent and by making use of its chemical reactivity, followed by recrystallizing the products to effect soil stabilization and solidification, and the resultant soil thus stabilized is converted to the aimed recyclable soil by using another chemical solvent.

The soil solidification and recycling is accomplished through such a practice that, for this purpose, a chemical solvent is used; it is characterized by redox action; by making use of the action, harmful compounds in the soil are decomposed and/or segregated and then recrystallized; thus the soil is subjected to phase separation and stabilized/solidified, the harmful compounds are converted to insoluble compound chlorides, crystal forms inert to ultraviolet radiation, or the like, that is, stabilized and solidified; furthermore, using another mixed material, soil suitable for water-permeable layer or water-impermeable layer or desired in recycling can be afforded.