When our soils sit for any length of time, we see that, the OM becomes localized near the suface, the sands shift downwards, and the clay rises with the OM.
It would be interesting to know how this new ground compares to nearby the tilled soils.
The thing that got me thinking about trying this is that this year we decided to make a garden in this same field. We got a late start and the sod was hard to break and turn under. We didnt soil test but I had pulled a sample a couple of years earlier in pretty close to the same area, so we worked off that. 6 in samples showed OM at 5%. Root depth I couldnt say, but the top 6inches where thick. We didnt hit any clay except where a drain line used to be before I dug it up and removed it. Soil looked like top soil from surface to bottom of plow line, dark and rich and plenty of grass roots. This is certainly the opposite to what the soil where the old garden used to be. Nobody lives in the old homeplace and the old garden is located on the opposite side of the house from where we planted this year. At any rate, we have been getting plenty of veggies with very little imput as far as ferts are concerned. Also very little insect pressure, grass coming back has been a bitc//.