I don't get the permaculture sphere's raging hard on for cardboard. Soils are my area of expertise, and the whole thing has me scratching my fucking head. Cardboard has a high C:N ratio, so right off the hop you're setting your system up for N immobilization.

But it breaks down fast!

This is because it's not very durable and quickly turns into small particles which are more rapidly acted upon by the microbial community. I get using it as a mulch, if you have literally nothing else, I guess. I would probably just till instead. Further, the 2-3 inches of wood chips they want to add would be sufficient to choke out weeds without the cardboard.

But wood chips also have a C:N ratio!

True, but their particle size is much larger, making them decompose much slower than cardboard. If you were to use sawdust (don't; C:N 500:1 to 1200:1 or more!) as an amendment, you would be in the same situation as cardboard, since it's very fine and has more surface area for microbes to act upon.

Ok, genius, what would you do?

Assuming you want a garden and don't want raised beds:

1. Soil test for nutrients, salinity, and metals. If good, then move to step 2. If not, raised beds. End of discussion.

But what about phytoremediation?

Generally not worth the effort, you still have to dispose of your contaminated plants, and they usually only hyper accumulate a few spp. Of metals.

2. till the shit out of my existing soil. This is likely 3" max of poor quality topsoil, underlain by compacted subsoil. Till to about 30 cm (or more if you can).

but tillage = bad.

Generally, yes. But this is shit soil to begin with and In this case we want to maximize soil drainage.

But I am worried about weeds

Don't be, we are gonna bury the mother fuckers. Tilling will also help with this.

3. Find any suitable compost or organic amendments I can with adequate C:N ratio. These are things like leaves, grass clippings, coffee grounds, composted manure. Soil test them to screen for things like salinity, pH, SAR, and metals. Apply heavily. Try and get another 10 cm or more of soil depth. This is going to be our growth media.

Now we have 40 cm or more of reasonably well drained soil, that's high in organic matter. Time to plant. Manually pull weeds as needed, or hoe (if you're ok with tillage).

What about this snake oil I've got sitting in my garage that I bought at the recommendation of some guy on FB?

Toss it. There are a lot of amendments out there. There are also a lot of quacks. I saw a guy pitching 'soil homeopathy' on a permie group. Another guy was going on about electroculture.... I can't talk about this, or I'll have to take another dose of my antidepressants.

Anyway, sorry if that was ranty, but I really like dirt.

Sounds like a really good plan!

We also have soil that isn't very conducive to growing. We used the same method about two years ago and are starting to see results. We still ammend the soil a bit when we plant directly, but there sure is a lot more going on in the soil now. It's super satisfying to see mushrooms popup in the wood chips!

If you ever find yourself with small logs or large branches, I recommend looking into Hugelkultur, which similarly involves building mounds of compostable organic material around large pieces of wood, which allows for the slow breakdown and release of nutrients over time

I might add a little compost to kickstart the breakdown or all that organic matter but sounds like a great plan!

I would make sure to look at the C:N ratio of your various layers to try to end up where you want. If it’s unbalanced it can cause problems.

Are you working off any guide, or mostly improvising?

I would just do the cover crops along with some nitrogen fixers for several years.

PS – I would keep getting the lawn clippings and use them to mulch my plants.