PROBLEM TO BE SOLVED: To provide a novel technique which can improve root spread of plants under over-humid soil conditions.SOLUTION: The invention provides a plant root spread improving agent in over-humid soil, the agent containing a microorganism-derived mixture in which a superheated steam-treated microbial material, yeast cell wall powders, and kieselguhr are mixed, the superheated steam-treated microbial material being obtained by subjecting a mixture containing a yeast, yeast extract, or yeast cell wall, and phosphate or a phosphoric acid compound and potassium or a potassium compound to a superheated steam treatment.SELECTED DRAWING: NoneCOPYRIGHT: (C)2016,JPO&INPIT【課題】過湿土壌条件下における植物の根張りを改善できる新規な技術を提供する。【解決手段】 酵母、酵母の抽出物、または酵母の細胞壁と、リン酸またはリン酸化合物及びカリウムまたはカリウム化合物とを含む混合物に過熱水蒸気処理を施すことにより得られる微生物材料過熱水蒸気処理物、酵母細胞壁粉末及び珪藻土が混合されている微生物由来混合物を含有する、過湿土壌における植物の根張り改善剤。【選択図】 なし
