Expanding applications of recovered fibers is indispensable to promoting the recycling of fiber products. In order to use spherical fiber assembly made from recovered fibers as hydroponic materials, the water retention of spherical fiber assembly itself as well as water absorbability of spherical fiber assembly in filling was measured. It was found that the water retention and water absorbability could be controlled by adjusting density of core-sheath conjugated fiber in fiber assembly with

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... % and more. Moreover, it was confirmed that spherical fiber assembly could make plants grow comparable to ball clay as hydroponic materials.