As many have posted yields vary heavily by season, for example my neighbor rents out his fields for field corn and hay production. This past year they planted field corn but weren't able to get back into the fields for spraying, too wet, and didn't harvest any corn, just brushhoged the corn this fall. So he's out the cost of seed, fert, and initial preemergent herbicide. They had no problem with the hay, only got one cutting in.
For what its worth, you might want to consider watching ag phd on the rural farm network, lots of interesting ideas and concepts to help farmers, especially with herbicides and manufacturer rebates.