| 摘要 |
PURPOSE:To provide the titled controlling agent composed of a powder containing calcined clay mineral containing an acid-soluble alumina, effective to kill or prevent the generation of algae such as green dust harmful to the growth of the rice in the growing period without damaging the rice, and useful especially to the treatment of paddy rice field for the direct sowing in a water-filled soil. CONSTITUTION:The objective controlling agent is composed of the powder containing (A) the calcined or uncalcined clay mineral containing acid-soluble alumina component and/or iron component, or (B) the partial reaction product of said clay mineral with an inorganic acid, or (C) an inorganic acid salt of Al or Fe. A product obtained by kneading an inorganic acid in a clay mineral preferably in the presence of water, and optionally drying the kneaded composition, exhibits remarkable effect at a relatively low rate of application. The generation of algae such as green dust, pond scum, etc. can be suppressed remarkably when the agent is scattered on a paddy field, and the algae can be eliminated within only several days. EFFECT:Since the agent contains silicic acid, it has desirable effect to promote the growth of the rice plant.
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