PROBLEM TO BE SOLVED: To remove defects of commercial crushed chip of wood and soil for horticulture which have low water-discharging property, water retainability and air permeability and prevent spreading of plant roots, because the commercial crushed chip of wood has hitherto been used alone in many cases and the soil for horticulture comprised a mixture of biological component of animals or plants with rock (mineral). SOLUTION: Melia Azadirachra L., tree chip, fiber or seed shell of Psoralea are mixed with iron oxide, titanium oxide, charcoal and copper in a prescribed mixing ratio instead of biological component contained in soil and minerals. Thereby, spreading of root is improved and further, environmental hormone (endocrine disruptor) and residual agricultural chemicals are decomposed and removed by action of titanium oxide, charcoal and copper to facilitate disposal thereof.
