To solve such problems that about 25 years are required for a bone to return to soil and, even if the bone returns to soil ideally, the actual return of the bone to soil can not be ensured physicochemically in a conventional technique and, therefore, a graveyard can not be recycled in a short period of time and the soil improvement of the graveyard is impossible and there is no proper technique for actually return the bone to soil physicochemically.

The bone is buried in soil as stored in a biodegradable run in which a bone decomposition accelerator is enclosed to decompose the bone and the urn at the same time in a short period of time to enable the soil improvement of the graveyard and the recycling use of the graveyard due to the synergistic effect of bone and urn components.