PROBLEM TO BE SOLVED: To prevent a harmful substance such as a sulfate ion from flowing out when covering a seed surface by an iron oxide, and furthermore prevent the seed from being burnt by reaction heat.SOLUTION: A material is granulated which is obtained by mixing seed, powder of an iron oxide, powder of the hydroxide of an alkaline earth metal, and water, and the mixture of the iron oxide and the hydroxide of the alkaline earth metal is made to adhere to a seed surface and solidified. Then, the hydroxide of the alkaline earth metal is made to react with a carbon dioxide to make a carbonic acid salt of the alkaline earth metal, and thereby the seed surface is covered by the iron oxide. The material is granulated which is obtained by mixing the seed, powder of the iron oxide, powder of the hydroxide of the alkaline earth metal, and water, and the mixture of the iron oxide and the hydroxide of the alkaline earth metal is made to adhere to the seed surface and solidified. Then, the hydroxide of the alkaline earth metal is made to react with a carbon dioxide to make a carbonic acid salt of the alkaline earth metal, and thereby the seed surface is covered by the iron oxide.SELECTED DRAWING: None【課題】種子の表面を酸化鉄で被覆するにあたり、硫酸イオンのような有害物が流出することなく、しかも反応熱により種子が熱焼けすることがないようにする。【解決手段】種子、酸化鉄の粉末、アルカリ土類金属の水酸化物の粉末、および水を混合したもので造粒して種子の表面に酸化鉄およびアルカリ土類金属の水酸物の混合物を付着、固化させた後、該アルカリ土類金属の水酸化物を二酸化炭素と反応させてアルカリ土類金属の炭酸塩にすることで種子表面を酸化鉄で被覆するようにした。種子、酸化鉄の粉末、アルカリ土類金属の水酸化物の粉末、および水を混合したもので造粒して種子の表面に酸化鉄およびアルカリ土類金属の水酸物の混合物を付着、固化させた後、該アルカリ土類金属の水酸化物を二酸化炭素と反応させてアルカリ土類金属の炭酸塩にすることで種子表面を酸化鉄で被覆するようにした。【選択図】なし
