The appraisal of real estate is not an exact science. It is the estimate of value of property as of a certain date.
Real estate is unique.
The differences in opinion of value reflect the individual interpretation of appraisers. Unless special use valuation has been elected under IRC 2032A, the decedent's interest in real estate must be included in the estate at its fair market value. The regulations define fair market value as the price at which the property would change hands between a willing buyer and a willing seller, neither being under any compulsion to buy or to sell and both having reasonable knowledge of relevant facts. Thus, use of the land for farming purposes might not be its highest and best use it were located within a good business area or within a substantial residential development area. It is your job to recommend the fair market value of the property.