wsmoak, I had my disc guy set the disc not to go into the base, so just a few inches deep, just the surface sand. Discs are adjustable, at least this one was. He used a Bobcat attachment. Not being a horse person he thought I was crazy because I “wasn’t going to get all the roots” but I explained how I needed the sand not to mix with the clay. He got it and did what I said. I supervised closely at first to ensure he wasn’t going to mess it up. Only a couple small fist-size clumps of base got into the sand in the whole project, and they were easy to pick out.
If your base isn’t done, you might consider discing the whole thing and then rolling it. I didn’t have tree roots to deal with, just some pretty substantial weeds with tap roots.
After discing, I ran the drag and raked out debris, ran the drag and raked out debris, ad nauseum. We also have icy winters here and can’t ride much, so it had plenty of time to settle over the winter and have matter rot out – at first it was a touch deeper than I wanted but I had it done in November and by this spring it was nice, not deep at all.
On that note, be prepared to get out there with a concrete rake and rake the plant matter out as best you can after disking and levelling. I took out a number of tractor buckets full.
This will only be relevant if you have serious weed overgrowth. I am still interested to hear about adding the salt as a permanent deterrent, I hope that poster chimes back in.