>>413370Well generally is to be done with marginal land is that the sales price of the output will be adjusted so that it reflects the marginal cost. The government would collect the difference in the sector as a rent that offsets taxes.
As far as renumeration for the farmer goes, it is trickier in agriculture, but not because of marginal land productivity differentials, but rather because of the uncertainty of final due to environmental effects (temperature, pests, winds, humidity, etc.) If those effects were removed the renumeration would just be calculated using the local productvity if that marginal land.
Eg. (40hour/week)*(50week/year)*(1/local average yield per year) = x hour/bushel wage
Obviously adjustable for number of harvests per year, crop type and standard working day, length, workweek length and number of weeks worked per year would be.