It sounds like you don't have anything that lives in the clay to bring the material down; your worms live on the surface in the decaying OM. You could try finding some soil dwelling worms nearby and transplanting them, but that may not work. A better option might be to inject OM into the soil by way of plants with impressive root systems, grown and then cut off to die and rot in the dirt.

It also sounds like your mulch may not have broken down. Was it matted and compacted? Was it broken into small pieces? If after one or two years you have mulch and clay and no compost, it seems like something is off.

Could you inoculate with healthy soil from a neglected area, where the animals and plants and microbes have been left to do as they will for a long time?

Looking at it from a mechanical point of view (more or less), you have the ultra-fine-particle plastic clay all by itself. What's "missing" is the medium particulate, the silt, and the coarse stuff, the sand. That all gives you a permeable drainable structure. Add organic material (OM) to the mix to, in turn, HOLD water. This view of soil requires three remedies: one bobcat, one dump truck full of sharp sand (50-50 with the clay) and a truck full of composted OM. Add a couple of years for things to settle in. This is a view appreciated by few people other than Impact Engineers and road builders.

The heck-with-it point of view says to ignore the clay. Flatten everything and bring in a thick layer of "topsoil" (dirt that ain't clay), perhaps arranging in raised beds for material economy. With a pickup you can work up one raised bed at a time.

First you have to leave all roots in. That is a very slow way to break it of course. But if you want to break it faster, there are a number of cover crops with tap roots. Some of these do have eating value. The best at breaking soil include tillage radish, alfalfa, sudangrass, and fava. Plant them thickly. A good way could be to plant any of these right after having harvested allium or potatoes in August.

Having the right amount of clay is beneficial to a building a productive garden bed, but when there is too much of it and too little of the other materials that make up soil, the very small particles become packed together so tightly that it becomes impervious to air, water, and even plant roots. Without oxygen, water, food, or space to move around, there will be no living organisms that are needed to build a healthy soil.

Simply adding mulch, regardless of the type or quality, will have little impact when there is too much clay and the bed has become too compact.

As the others have said, you need to start by getting the amendments mixed in to what you have for them to be of any use. Once tilth has been improved mulching will become a much more effective way to build better soil.

AMENDING CLAY SOILS

How to improve clay soil

Estimating Soil Texture

If you were to search this forum for 'clay soil' you would find some extensive threads about this problem. But the advice posted here so far is on target. I did a lot of digging and tilling for several years to incorporate organic matter. After awhile you can reduce digging (which destroys the spongy structure you want to develop) and rely more on mulches.

This is why I am such a fan of tillage radish (daikon), Tox. It is because I too did a lot of digging. But if you are willing to stop growing in mid-summer, and spend the rest of the season growing soil, then you can biologically drill. It still takes time.

Thank you for the links.

Mix with lime

When I started gardening many years ago, I had totally hard clay soil. We had to do raised bed gardens due to the gopher population. I then started composting.

Unfortunately, we had a rat problem, due to our neighbor's infested barn, so I had to move the compost bin away from the house.

When I dug into the area that the compost pile was, I was totally amazed that I could dig down more than a foot in the area that the compost pile was located!

Normally, in our clay you would have to dig a few inches, add water, wait a day and repeat......over and over!

Now I move the compost from bed to bed and spread the wealth! Nancy

wood chips wood chips wood chips.....that is your answer.....woodchips brings in all kind of critters like worms that loosen clay soil. Check out back to eden garden and lasagna gardening

Wood chips could work, as long as one understands they are a mulch that will require time. wood chips are not a soil amendment, something that you mix into soil, unless you are prepared to add enough Nitrogen to that to help the Soil Food Web digest them.

Compost, and other forms of organic matter (vegetative waste) can be soil amendments and generally do not need large amounts of Nitrogen added when mixed into soil.

kimmq is kimmsr

Someone recommended lime. This should only be done if the soil is too acidic. Which you will only know if you have a soil test done. Lime is not a universal cure and if your pH is already neutral (or, heaven forbid, alkaline), it will do more harm than good.

If you have sodic clay (which your local ag extension people should be able to tell you), you can add gypsum to break up clay. Calcium without the alkaline effect.

Raised beds filled with organic material, and let time and roots and worms solve the problem.