The problem with that is you begin valuing the operation, management, and going-interests of the farming operation, not the value of the farm land. The land value in and of itself is the capitalized rental return.
There was one appraiser on this forum that routinely valued the total operation as the value of the land, and was always in hot water with the state board.
Remember that land is only a part of the "bundle" in the farming operation.
Consider the "valley" farms in CA. Right now the farming operations are dependent on irrigation, with federal EPA, state regulators, etc trying to reduce or eliminate in some cases irrigation from rivers. The water is another piece of the "bundle" that if you take it away, the production drops to zero. Same with management. Bad management, no viable operating farm.
Just remember that, like a manufacturing plant, the land value is the income attributable to the land through capitalization of the rent, sales of vacant land, or land extraction method of overall capitalization after extraction of the farm operation.
