Deductions & credits

I understand your calculation, but that seems to indicate I have given up ownership of the donated property.  In my case, I still own the property and have use of it and can sell it.  However, I cannot subdivide it or build on it.  I can still farm it, cut timber etc. In my case, I have placed an easement 22.3 acres of a 24.3 acre parcel.  The value of the parcel dropped $90,000.00 when the easement was executed.  Maybe my original cost basis should drop by a proportional amount?