All types of soils, farming practices and numerous subsoilers. I had an airline pilot farmer nearby with a 105 White and a 3 shank that looked to be 3' long. I like the Hay King Pasture renovator and is my primary "plowing" tool which I run around 8", give or take, deep.
On farm sites I read where folks with places such as yours do what you are intending to do and get positive results.....makes sense. I'm remembering the author of the piece was running pretty deep....forget just how deep.
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What is plow pan? I don't technically know but expect it is the interface of soil (clay) that goes untouched from year to year adjacent to soil that get things that go say 4-6" deep year to year. Since 6" is where most roots grow and plowing costs money, why go any deeper???????
I'm in Houston Black Clay, some of the nastiest stuff you want to fool with when "it" doesn't want to be bothered. In the summer it cracks open and some of the cracks are 6" across at the top and as long as you care to follow them in lateral length. I have attempted to find the bottom and gave up at 6 feet on some of the larger ones. These cracks allow nutrients and moisture to penetrate well below the root zone and allow water to be stored for clay's bright spot....providing moisture for late summer crops.
When the rains come and fill up the cracks the clay essentially melts and becomes one gooey, muddy, blob of a mess. This mess eventually solidifies and seals off a lot of the "loosening" efforts of the past. The only way to make it percolate is to add dry matter. Texas A&M U. (TAMU) Ag. Extension Services publishes many "letters" on how important it is to mold "plant stubble" into the soil (rather than burn it off....the easy, non productive way to get rid of crop residue) to provide humus and break up the soil.
My current practice is the renovator running "contour" to the terrain in the fall when the clay is hard and responds to the blades. (If you try to renovate when too wet the hole just closes behind you.) As long as it is dry when you renovate, over the following month or so, the soil will actually crack open along the seams that the renovator sliced through the soil (with minimal surface disturbance thanks to the coulters that precede the shanks).
If I am doing a hay meadow, that is where I stop the tillage and come back with commercial fertilizer just before a rain. This combo does two things: Catches what otherwise would be runoff and allows the fertilizer that hasn't already been absorbed into the soil (or evaporated) to move into the root zone with the following rains. That's it for that.
If putting in a cash crop I then run a 3 pt tiller over the soil with the gate open at a moderate speed to incorporate the stubble into the top several inches of soil....stubble is from hay production, not stemy small grains so there isn't a lot of it. Soil is much more uniform as compared to running a tandem disc which, in the fall is almost useless, weighted down or not, as the clay is hard and penetration is minimal.
I can do with one pass of the tiller what it would take several passes with the disc harrow and the results are smoother and more uniform. Follow on is with a spike harrow which could be attached to the tiller for a one pass operation. I don't usually include the harrow with the tiller as I come back with commercial fertilizer (broadcast) and then run the harrow to incorporate it and reduce evaporation. Last pass is drilling the seed.
