How many loads does an average farm produce? I assume it depends on the soil, so what if the farm is on "light green" soil?
As Jamon_Del_Guapo implies, which overlay setting is 'light green'? Do you mean the "eye" of the building? If so, that is the composite of fertility and wetness; and 'light green' means less than the best, but a little better than marginal. Certainly less than the average.
Look at all the soil factors:
- fertility (reduced by pollution)
- current wetness
- average wetness (over 80 years)
Also, different crops produce different loads on different cycles.