Ohio Rev. Code § 5713.04
Each separate parcel of real property shall be valued at its taxable value, excluding the value of the crops, deciduous and evergreen trees, plants, and shrubs growing thereon, and taking into account the diminution in value as the result of the existence of any conservation easement created under sections 5301.67 to 5301.69 of the Revised Code. The price for which such real property would sell at auction or forced sale shall not be taken as the criterion of its value. If the fee of the soil of a tract, parcel, or lot of land is in any person, natural or artificial, and the right to minerals therein in another, the land shall be valued and listed in accordance with such ownership in separate entries, specifying the interest listed, and be taxed to the parties owning the different interests.
If a separate parcel of improved or unimproved real property has a single ownership and is so used so that part thereof, if a separate entity, would be exempt from taxation, and the balance thereof would not be exempt from taxation, the listing thereof shall be split, and the part thereof used exclusively for an exempt purpose shall be regarded as a separate entity and be listed as exempt, and the balance thereof used for a purpose not exempt shall, with the approaches thereto, be listed at its taxable value and taxed accordingly.
The county auditor shall deduct from the value of each separate parcel of real property the amount of land occupied and used by a canal or used as a public highway at the time of such assessment.
R.C. §5713.04