There are a lot of potential answers to your questions. Was your lease prepared by a professional? If you are a surface owner and a mineral owner, the time to address the surface use is at the time of lease execution.
As to hay, multiply your yield per acre times your net revenue per bale times average crops per year to get a one-year minimum damage rate.
The average lease provides damage for growing crops and timber and does not take into account taking acreage out of production.
Most farm-raised boys who are in this business can write volumes about this subject.
Buddy Cotten