Except as otherwise provided by law, for the purpose of assessment, real and personal property shall be appraised at its fair and reasonable market value, according to the best judgment the assessor, the board of equalization, and agents of the Department of Revenue can form upon information, inspection, or otherwise, taking into consideration all elements or factors bearing on such value as heretofore or hereafter authorized; mineral, coal, oil, gas, timber, and turpentine interests, when they have been severed in ownership from the soil, by sale or otherwise, shall be separately appraised and assessed. Notwithstanding the above, all property under lease as of October 1, 1978, which lease does not provide for a direct passthrough of property taxes to the lessee, shall be appraised solely on the basis of the economic net return to the owner.