Not only that but you have to rotate what is planted in fields or you'll basically decimate the fields productivity.

The guy putting in hay just got unlucky this year. I grew up on a farm, this isn't unheard of. Also sorghum doesn't grow well in all areas, where I lived corn and barely/wheat/rye were the best crops. Sorghum grew, just not all that great due to growing season. We never ever planted the same field twice in a row with the same crop. Some years we left it fallow (nothing planted) to give it and the microorganisms a rest.

I think the parent poster lacks some fundamental knowledge of crops with his analogy.