PROBLEM TO BE SOLVED: To provide a soil-improving material in the improvement of an acidic sulfate soil, improving the acidity of the soil by accompanying with progress of its oxidation also so as not to inhibit the germination or growth of plants. SOLUTION: This soil-improving material is obtained by forming an artificial zeolite by performing a hydrothermal reaction of incineration ash with an aqueous solution of sodium hydroxide and ion-exchanging the artificial zeolite with a prescribed cation for reducing the content of sodium ion to≤6 wt.%, preferably to 2 wt.%. The acidic sulfate soil is improved by adding water to the soil-improving material to make slurry and spraying the slurry on the surface of the acidic sulfate soil. Further, the acidic sulfate soil is improved by mixing the soil-improving material with a growth base material and spraying the growth base material on the surface of the acidic sulfate soil. COPYRIGHT: (C)2007,JPO&INPIT
