Mulch. Lots and lots of it.
If you somehow break your soil up, by tilling or a broad fork or any other mechanical means, it will still remain clay. In a million years, it will still be clay. Any mechanical tillage will just revert to brick-hard soil with the first rain and the first heat-wave.
The structure of clay is a very small, negatively charged particle. Because it's so fine, clay is a fantastic material to make pottery or tile from. Once you fire it, it will last for thousands of years. But what makes great
coffee cups does not make great garden soil. The negative charge causes the clay to form long chains --- imagine a stack of paper plates, one against the next with no airflow between them. That's how clay bonds together tightly. Air and water have a hard time pushing their way through these tightly bonded plates of clay particles.
The secret is to integrate
carbon down into the clay. It breaks up those long stacks of clay particles and allows water and air to move down into the soil profile. OK --- so how do you do that?
Nature does this through a variety of means. First, plant
roots can push their way through clay when it's wet.
Trees actually grow very well in clay, but not when it's dried out like a brick. Weeds are your friend, as they are punching their tap-root down into the soil profile and pushing carbon throughout. Not only are the roots themselves carbon, but the plants are secreting
root exudates to attract beneficial microbial life. The exudates
feed bacteria and other microbes, further bringing more carbon/more life into the soil.
Second, a cover of leaf litter and dead bio-mass on the surface of clay soil (plants that die due to thirst or winter or some other means) slowly breaks down until humus is formed. Humus is a highly stable form of carbon that is left when decomposition stops. It's a black, jelly-like, substance that holds 8 times its weight in water. Basically, once those leaves rot down to humus, they create little globs of water-retaining sponge. Less than 3 percent of the bio-mass that decomposes eventually turns into humus, so it takes a great deal of mulch on the soil surface to raise the long-term percentage of humus in the soil.
Third, earthworms, mites, arthropods and other soil organisms love to eat the organic material on the surface of the soil (mulch) as well as the decaying roots under the soil. They eat,
poop, tunnel, poop and eat some more. If you put a thick layer of mulch on top of your hard clay soil, you will notice a tremendous increase in the number of earthworms that are present in a short time. In just two years of mulching, you'll be shocked with how many worms there are, and how active they are even 6 or 8 inches below the surface of the soil. They are grabbing biomass from the soil surface and pooping it out deep below. As it is eaten and passed through their digestive tract, that carbon is mixed with all sorts of enzymes, waxes and bacterial life. Mulch drives the entire system forward. If you don't have that carbon on the top of the soil, you won't have the life happening below.
So ---- be grateful for that wonderful, nutrient holding clay! The negative charge of a clay molecule will hold nutrients like N, K, and P, but only if there is also sufficient carbon also present in the soil.
Do this:
1. Find a cheap source of plentiful mulch, and begin putting it down on top of your hard, lifeless clay soil. Mulch heavily. My drug of choice is wood chips. I get them by the truck load from tree trimmers that I find working in the area. I speak with the foreman of the crew, get them to agree to save a trip to the dump and bring them to my house, and then I'll sit there and wait for them to finish their job so I can lead them back to my house. Over the years, we've gotten at least 100 loads of chips, and then have patiently wheeled them into the yard/garden/orchard one wheelbarrow load at a time.
2. Try to keep a living root growing in the ground at all time. Where we live, we can grow 12 months of the year. As soon as one crop is harvested (or even before), the next one goes in. During the winter, I plant a thick cover crop wherever there is bare ground. In the spring, I'll chop and drop that to add more biomass to the soil surface, leaving the roots in the ground. In as much as you can, don't pull plants up—chop them off at the soil surface and leave the root to decompose in the ground. Weeds are not all bad. If they aren't bothering anything, let them grow, and then chop them off as they get ready to seed.
3. If you don't have comfrey growing somewhere on your property, get some. Plant it all over. It's a great companion plant. It produces a lot of biomass that can be cropped and dropped. It sends a deep tap root through heavy clay soil and mines the subsoil for nutrients. Don't buy a lot of crowns -- just a couple. Within one growing season, you can divide that crown into a dozen plants or more with root cuttings.
4. All decaying plant material eventually gasses off, so your mulch will need to be replaced regularly. The worms will pull some of that carbon down into the soil, but much of it will just return to the atmosphere. That's OK -- just keep mulching (most likely 2 times a year, once the microbial community really starts to thrive in the rich environment you create for it). You'll want to keep the mulch slightly moist.
5. I need to talk about fungi here somewhere. Mulch and decaying plant roots, along with the living roots of trees and other herbaceous plants will feed fungal networks below the soil. Fungi is actually closer to an animal than it is to a plant (which might give some vegans here cause for pause). You WANT to establish an extensive fungal network below the soil. All that mulch will feed the fungi. If you see a flush of
mushrooms popping up after a hard rain, that's a good thing. If means that the fungi is below the soil and throughout the mulch, doing its thing. Fungi are also bringing additional carbon down into the soil, but also they are secreting a chemical that binds soil particles into little aggregate clumps. (Root exudates do this as well). Why is some soil crumbly like cottage cheese or coffee grounds? That's the effect of root exudates and fungi exudates.
6. DO NOT till your mulch under. It's a waste of time and
energy, and it will actually tie up nitrogen in your soil if you do so. You don't need to. The worms will do that for you, but it'll take a few years. Patience, grasshopper. No till is the best thrill.
Mulch is
the answer to your question. Give it a couple of years and you'll be completely shocked with the transformation you'll witness in your hard, dry clay soil.
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