Hay crops have changed a lot over the years. Grew up in southern Mn, next to the Corn Patch border. I have been away from the farm since 58. Dad died of cancer winter of 58-59, my brother was in Army, I was to young at the time to take over, & between me & Mom, we didn't know enough about the operation to make a success out of it.
In those days, grass hay was considered junk, suitable only for horses. Alfalfa or clover hay was considered too rich for horses, made them fat & lazy. Since Dad was the only one in neighborhood that still had horses, we harvested road ditch grass for them. Grass hay was free. Beef & dairy cattle got alfalfa or red clover hay. No one expected to get a hay crop the year it was seeded. It was worked into the corn, soybean, oats rotation. Hay ground was plowed down as "green manure" after being harvested 3 or 4 years. It was seeded with oats, or flax, as a "nurse crop". Harvest the oats/flax, & if a late fall season, get a cutting of hay off it the same year.
The thinking at the time was that alfalfa/clover was more efficient use of the land for beef weight gain or milk production. Just rambling.