A recent trip to Oklahoma to coach two teams of soil judgers left me understanding why the Natural Resources Conservation Service has such a big challenge. The agency has to know how to slow down erosion in the Midwest, in places like Indiana, and in the Southwest, in places like Oklahoma. There are still soil erosion problems in both locations.
In Oklahoma the soil is orange to reddish from the top to the bottom in some parts of the state. Where the soil is orange, the water in nearby ponds and lakes is likely to be orange. That's because soil runs off there just like it runs off here, maybe more so.
In many of the pits we judged in Oklahoma, there was half or less-than-half of the topsoil left. Most of the places we judged were in grass or some sort of conservation use today, but earlier times took their toll. The scars of dust bowl days are still there, if only in the form of diminished topsoil.
On one farm we found brown soil, more like you would find in Indiana. Almost all the topsoil was still remaining, even though it was a 6 to 9% slope. In Oklahoma slopes tend to be longer, so that's enough slope to cause erosion problems.
Why was this soil not eroded? Likely because it was a native grass field. To the farmer's knowledge, it had never been plowed. Today he makes shay from it. The grasses are warm-season, perennial grasses such as Big blue stem that are hard to establish here, but native to the southwestern states.
We saw a few old terraces and a lot of cattle. Keeping that soil covered with grass is likely the best way to prevent more soil erosion. But we still saw the red lakes. Just like in Indiana, not everyone has apparently figured out how to stop soil erosion yet.