Planting large trees in swales on heavy clay soil

I live in central Missouri(Zone 5B) and I'd like to plant a nut orchard with chestnut, improved hickory, walnuts, and hazels. The area I'd be planting already has some hickory growing on it along with some oaks and small maples. It's on a slightly sloping ridge where the soil is maybe a couple of inches of darker clay soil and then underneath is orange heavy clay soil. I imagine the hickories will do fine, but I'm concerned about drainage for the other trees.

I read a few places on the forums here that planting into mounds made up of soil with a relatively high clay content so it bonds to the regular soil underneath can work. Right now I'm thinking that I'd build swales and plant the trees along the tops of the berms, but how deep do you think the mounds should be? Should I widen the berms around where I'd plant the trees? If so, how much? And since these trees will potentially be 50' tall, should I be concerned with them not anchoring well and falling over?

I kind of just did what my tractor was capable of in my swale and berm making but my berms are about 2-3 feet above the bottom of the swale and are probably 2-3 feet wide. Made with the bucket of a tractor. Digging around in them this fall I found the roots of the trees I planted in them went right along the contour of my berm and all the way to the bottom of the berm. I have heavy clay too. Just disturbing it appears to have loosened it enough to grow all sorts of things for me and no root rot yet. Probably helps that I don't exactly water them much.

Are they going to be large trees? Did it look like the roots were growing into the original soil underneath the berm at all?

Tao Weilundemo wrote:Are they going to be large trees? Did it look like the roots were growing into the original soil underneath the berm at all?

I have some black walnut planted in swales and they get large but right now are just whips. The bigger trees right now are just standard sized fruit trees, but again, I just planted. I did not dig that much around there. I was transplanting grapes which is the only reason I dug at all. I encountered a lot of roots though and I was transplanting onto the edge of the berm so the roots went quite far and I only planted my trees in July of last year. So pretty impressive if you ask me.

I will say I have had some leaning issues but I think that is probably wind related. Most of our trees are tilted at least a little bit from the wind. I'll probably have to stake some of the farther leaning trees. Otherwise it's doing ok.