Man you're a digger. I dug for days around the house over the years. Something about it for me that's fulfilling. What do you do with clay? It's so dense . It sounds like you are going to create a super grow environment. It 's strange you didn't find worms. You're going to have a garden space to behold when you're done.So since I moved up here to Oregon from CA I have been kind of obsessed with getting the soil in my backyard as good as I can get it. My old yard was infested with gophers so my only in ground option was in my 8 ft x 8 ft greenhouse. I didn't put in a floor just dug it out and lined it with Gopher wire. When I did I had to go down about two feet. The clay layer there was like potters clay and it took along time to get it into decent shape. Lots of compost, manure, peat and some Gypsum to help break up the clay. I had it in pretty good shape and then I moved here.
The soil here is a red clay base but nothing like I had in CA. The Willamette valley was a flood plain. When I started digging I found all the rocks to be like those you'd find in a riverbed. I'm not much for soil testing but I do have a simple PH meter. It was in the mid range. The beds were for the most part rotting and when I was digging up the soil I found that in each bed they had put that fabric membrane in the bottom of each bed. I'm not sure why they put it in as all it was doing was keeping worms out of the beds. I dug them all out and added some new beds. It was a lot of work digging down and amending below the grade level but I wanted to do it right the first time. I have piles of stones that I pulled out. The good news was that I didn't have many tree roots to deal with. There was one thing I did notice and that was a total lack of earthworms when I dug down a ways. So that is one of my goals to get plenty of earthworms in the soil. I did all the soil work this last spring so when I amended the soil I did so that I could grow vegatables and cannabis this season. So in the lower level I used compost, peat, manure, gypsum and some lyme. When the season is over I'm hoping to do an experiment.
I have been reading up on winter mulches for beds and cover crops. There are tons of leaves here in the fall you just have to get the right ones. Nothing too acidic. I also got my hands on a couple bales of straw that hasn't been treated with herbicides. I'm hanging onto plain cardboard and I'm saving coffee grounds. I also get them for free from the coffee houses. What I'm hoping to do if my back holds up is do dig out the beds again before the rains set in and layer coffee grounds, manure, leaves, straw and cardboard. Put the dirt back in and plant a cover crop. I will have a good five months for everything to decompose.
I have looked into buying worms but most are for compost piles red wiglers. There are night crawlers which are regular earthworms from what I have been able to read so I may get some of them and throw them in when I'm done.