4.2.2.2. Physical Components.Buildings and improvements, timber, crops, sand, gravel, minerals, oil, and so forth, in or upon the property are to be considered to the extent they contribute to the market value of the property as a whole. “[I]t is firmly settled that one does not value the [ ]land as one factor and then value the improvements as another factor and then add the two values to determine market value.”244 Rather, the measure of just compensation is the market value of the entire property— not the total of the money values of the separate items. As a result, in developing an opinion of value for federal acquisitions, the appraiser must consider all the elements that “contribute to make the property valuable, all . . . that detract from it, and finally, weighing all those elements, determine [the market value of] the single piece of property . . . .” acquired.245 

The unit rule is often misapplied in valuations involving natural resources such as minerals, oil, and gas.246 As with any other component, the possible or actual existence of such resources can only be considered to the extent it would contribute to the market value of the whole property. Section 4.8 discusses valuation issues that commonly arise in appraising natural resource properties.