Agricultural engineers at Iowa State College get many requests for a method to estimate the amount of tractor fuel needed for various field operations. There just isn't any really simple way to do this. But here's some help:
Iowa Farm Science Editorial Board
"How Much Tractor Fuel for Field Work?,"
Iowa Farm Science: Vol. 11
, Article 10.
Available at: https://lib.dr.iastate.edu/farmscience/vol11/iss7/10