Blair, remember that this little patch of a place where I farm was built by a flooding and receding, young river. The ever changing channels giveth and they taketh away. Soils here run the gamut from sand so pure you can scoop it up, dry it, and use it in your sand blaster - all the way to soils in the bottom of the old oxbows that are so rich in OM that you can't make a mud ball from them, even if you can wring water from the handful you're trying to ball up. Of course there are also some that are sticky clays and some that are only suitable to work for a half hour each year; and wouldn't you know that half hour always comes at lunch hour  The one good thing about flood built ground is that we don't have any of those things you folks call rocks.

The other thing that's critical about killing weeds with iron is working depth. Way more weeds are missed by going too deep and having them transplant, than are missed by going too shallow and sliding over them. If you pay close attention to eliminating ridges and humps and holes, it is easier to maintain a 1 to 2 inch working depth. Leaves more mulch on top, preserves the soil moisture with a bit of a dust mulch, and if you're not digging it up, it ain't drying out. Having a tillage tool that flexes every which way and follows the contours is important here. You and I both know that Terry F. had the answer there.