I've been reading and searching. I've found tons of useful info, but not exactly answering this particular question.
I have heavy clay soil, and wanted to build up hills with holes beneath. I plan on mixing my local soil with topsoil and black cow manure. I don't know if I should do an even 3 part mix, or half local soil and 1/4 topsiol, 1/4 manure. I'm also going to lay some wood ash on top, and then a healthy mulch layer. So, my first question would be which of the two mixes mentioned above would be better.
And now my main concern. How deep a hole chould I dig vs. how high a hill I should build. I plan to use the leftover straight local clay I dig up to build a dam uphill of each hill to avoid washing out in heavy rain, which happens frequently with late spring and summer t-storms. My local clay just doesn't absorb all that much and runoff is a potentially huge problem. Which is also why I want to build hills, to keep the crowns above that possible saturation level.
Any advice would be greatly appreciated, as my 9 rizomes came in today, and they go into the ground this Sunday. It's going to be a digging, mixing, BBQ and homebrew extravaganza, and if anyone local is interested in coming by, PM me!