It is interesting what different areas of the country have for soil. I can find 6 inches of sandy loam across the street in the unclaimed property I mow. I have a small area of that sandy loam in my property. The rest washed away before I got it. I made a 3 shank subsoiler and my tractor will stop when I am in clay. Most of my little 9.3 acres is red clay with a hint of topsoil. Even a single shank will bog out the tractor. OK, my tractor might weigh 3,500 pounds and has short 11.2x24 tires which means it has limited pulling abilities. My uncles, who are farmers say that the taller tires give you more pulling ability.
Anyhow, whenever the farmer across the street or the neighbor down the road pull a plow or disk, they pull up rocks. The neighbor probably learned his lesson as that is a lot of work to clean up a pasture after turning up rocks. One of my hay farmers 30 miles away sold his Pasture King airator because it pulled up to many rocks. I do not see any rocks in the family farm fields up in eastern Indiana.