PROBLEM TO BE SOLVED: To provide a method for producing culture soil containing 30-90 wt.% of granulated coal ash as a raw material without using any binders, and having a porous structure. SOLUTION: The method for producing culture soil comprises the following steps: mixing granulated coal ash with subsidiary material such as perlite, vermiculite, zeolite, sand and the like, having an expansion coefficient different from that of coal ash; kneading the mixture to be a muddy state having 60-70 wt.% of water followed by aging the kneaded mixture; granulating the resultant mixture in a state of having 30-50 wt.% of water to form granules each having a diameter of about 5 mm; irradiating the granules, just after the granulation, with microwaves for 15-25 min so as to sterilize fungus and seeds; and drying the thus treated granules to be solidified and have a porous structure in the inside of each granule so as to have a moisture content of≥50 wt.%. COPYRIGHT: (C)2003,JPO
