PROBLEM TO BE SOLVED: To provide a technique for improving soil which can be improved to culture soil having a high quality, exhibits water discharge performance, permeates rain water into the ground naturally and swiftly, hardly generates a frost column in the winter season, includes water retention, and has an advantage excellent in safety, solidification, duration and low cost performance when improving construction sludge and construction remaining soil such as a cement milk residue and bentonite a large amount of which is generated in a construction site. SOLUTION: The technique for improving the soil comprises introducing a primary granulation accelerator mainly composed of the fly ash of a wood chip and paper sludge into the sludge and the remaining soil to mixing it to generate a primary mixture, and introducing a secondary granulation accelerator mainly composed of a microbe material into the primary mixture to mix it to generate a secondary mixture, wherein the secondary mixture is fermented in a fermentation tank to generate the culture soil. COPYRIGHT: (C)2007,JPO&INPIT
