The best soil I've ever seen was that made by a soil scientist friend who used yard waste, e.g. whatever landscapers gave him.
Piles of flowers, wood chips, etc.
He would patiently mix it up and also add duck manure and feathers and chicken parts from a poultry operation.
The feathers and other parts stank the worst, the smell of death I guess.
Anyway, he composted it, paying attention to particle size etc. Adding water, keeping the piles at 160 degrees F.
I got some of his soil and did amend it a little. Added Jamaican bat guano, the high-phosphorus kind.
I tried to imitate his techniques and got some decent soil with a carbohydrate rich mix of about 4 cubic yards.
1 cubic yard of wildflowers, literally, from a landscaper neighbor.
1 cubic yard of red berries on branches. The kind you see used all over suburbia in bank parking lots etc. Which is where I got them.
About 50 pounds of potatoes, they were on sale
Garbage cans of fruit pulp from the smoothie place.
I also added wood chips, some of them with manure mixed in. The garden I was doing this in was part of a church and they gave a large landscaping company permission to dump all their wood chips.
Then I would have literally 50 piles of different blends of wood chips to pick from.
When it rained, a few of them would heat up and steam very obviously. Those are the ones I took my wood chips from.
I didn't know it but I was making a mix that would heat up slightly, like to 130 F, and then become a home for the worms. They went crazy for the potatoes, smoothie extras, red berries, etc.
Wood chips are often real easy to get. They can make a great soil input but they need nitrogen to offset the carbon from the wood chips.
Anyway, the point is you can make such great soil with components that people give away free - or pay to dump somewhere.
I found that it helps to give the pile access to the dirt ground, so that redworms can crawl up into the pile of soil-in-process.