You'd probably want to get to grips with weather reports and find
details on crop yields, alternative grains, plus transportation costs.
Building
on earlier research showing the carbon payback time of biofuel
crops grown
on certain types of land, the new study uses «a new, geographically
detailed database of
crop locations and
yields, along with updated vegetation and soil biomass estimates, to provide carbon payback estimates that are more regionally specific than those in previous studies,» write the authors.