It all depends upon what you can do with the land. If he can build 10 units on it makes a big difference as opposed to whether he can build one house on it.
A good comp might be the pumpkin patch owned by the SRF or even the agricultural land they own off Summit. I know someone that has done some analysis for them (even though publically they say they will never sell it). It might take some time but I’ll see what I can find out.