Offhand, you'd expect improved farms- farms with buildings- to rent for more than unimproved farms- farms without buildings. But this doesn't seem to be true.
Toussaint, William D. and Timmons, John F.
"How Much Rent for Unimproved Farms?,"
Iowa Farm Science: Vol. 8
, Article 3.
Available at: https://lib.dr.iastate.edu/farmscience/vol8/iss1/3