Realistically, most dryland wheat farms produce about 25 bushels an acre on average. Irrigated wheat farms can produce upwards of 60 to 70 bushels of wheat per acre. I don't know anyone with yields higher than that. Southern Walla Walla County has some of the best soil conditions for wheat I've ever seen (a rich Loess soil and plenty of ground water for irrigation). When they grow wheat there, they get about 65 bushels and acre. I'd think that is the optimal yield for the amount of effort necessary. I am sure you could get more out of the ground, but the effort would be along the lines of diminishing returns for the effort expended.

The article only reinforces my earlier point.