Here's a method you can use to estimate the value of adding acreage to your farm. Starting with data from your farm account records, an 8-step procedure indicates about how much you can afford to pay for more land.
Hurlburt, Virgil L.
"How Much for More Land?,"
Iowa Farm Science: Vol. 13
, Article 7.
Available at: https://lib.dr.iastate.edu/farmscience/vol13/iss2/7