On my farm I usually rotate the ground year to year. I have hay, oats, soybeans and corn. The corn is usually planted into the soybean ground. The soybeans go into the corn ground. When we need to rotate the hay. We spray and kill the hay in the fall and then plant corn in the spring in that ground. When we start a new hay seeding we plant oats as a nurse crop with alfalfa and brome grass into last year's corn ground.
The difficult part is that some of my ground is steep enough that you can not raise soybeans on it so you have to have it in hay or corn. I have about 100 acres of hay. So I try to seed down 20-25 acres each year. So the steepest ground is usually in hay. It makes planning the crops a brain bender at times.
My sons raise most of the crops on the rented ground. Usually we are just in a corn soybean rotation there. Until just the last 4-5 years we would have been in a 50/50 rotation. Now it is about 2/3 corn with a 1/3 soybeans. So it is two years corn with one soybeans now.