PURPOSE: To provide a soil conditioner which promotes the crumbling of soil and in which calcium sulfate properly acts over a long period of time, by a method wherein a cell org. material, which is obtd. as a by-product from beer brewing or antibiotics production, is mixed with calcium sulfate, and the mixt. is granulated.

CONSTITUTION: (A) A cell org. matter (e.g. a used medium composed mainly of a soybean cake) obtd., as a by-product, from fermentation industry, food industry or wood pulp industry, is mixed with (B) a fluid product of the acid-discharging treatment of calcium sulfate in a reguired ratio. The mixt. is granulated and dried to obtain the desired soil conditioner.

EFFECT: The org. matter serves as a buffering material and the calcium sulfate properly acts on soil and crops. The pH of the soil is stably kept over a long period of time. Injury caused by salts can be eliminated. Amino acid and ribonucleic acid contained in the org. matter promotes the growth of a plant.