| 摘要 |
PROBLEM TO BE SOLVED: To efficiently cultivate the same useful plant high in added value in large quantities in the whole region of the same water channel simple in constitution and constituted so as not only to be capable of being easily adapted even to an existing water channel but also to be capable of preventing the generation of algae while maintaining the surface of the water to a light cutting off state without requiring a water sprinkling pipe and laminating culture media comprising different materials to collectively recover the same. SOLUTION: The whole region of a water channel 1 is directly packed with an natural mineral filter material 24 so as to form a filter material bed higher than the surface WL of the water and the packing height of the filter material is changed corresponding to the moisture resistance of a useful plant 27 to be cultivated to cultivate various useful plants having high water purifying function and different growing periods or the same useful plant 27 high in resource value in the whole region in the water channel 1 and water is efficiently and stably purified by the useful pant 27 and the natural mineral filter material 24. |
