well, it is a soil that will make you happy after you break it. By far the best way to break it is to plant cover crops with deep, penetrating roots. Second best, if you have the means, is to trench it and drop large chunks of wood deep, a technique called hugelkultur. It depends on what you want to do with it. Lawn? Beds, vegetable or flower? For the former cover crops is the real winner. The latter, hugelkultur will give you instant (well, one year) deep soil.

Typically, the recommendation you will see most often given to lighten and loosen heavy clay soils is the addition of a sufficient amount of coarse organic matter. This can be the barky types of bagged soil conditioners, a less than completely finished compost (still has some larger pieces and numerous twigs, etc.) or by simply incorporating something like wood chips well into the soil. If you need a quantity, the two latter materials are often found in bulk and in the case of wood chips, often for free from tree trimming operations.

Incorporating OM results in an almost immediately workable soil - no waiting for rooted cover crops to grow and penetrate the soil profile nor the time it takes for huglekulture to do its thing - but does require a bit of effort (elbow grease!). And if you use just the wood chips, you may need to supplement with some sort of high N source - urea, urine, blood meal, bat guano, etc. - to offset some temporary nitrogen tie up.

Am interested in hearing what works for you as I have the same problem.

First, as Glib said, embrace your clay. It is full of organic residue and minerals - a much better starting point than a light sandy desert or coastal soil. Mostly, you want to improve the tilth. You do this by adding both hummus (finished compost) as well as unfinished compost (to encourage worms, beetles, and other small scavengers).

You also want to add calcium and reduce magnesium. Magnesium particularly locks clay particles together so at all costs AVOID DOLOMITE LIME.

While I am a big proponent of no-dig gardening, I usually dig twice when I have to jump-start a poor soil. After that, we can leave it alone and let the roots, fungus, and bugs do all the digging.

This would be my plan for preparing your beds for planting in spring 2017 without spending much money.

1. Starting now (spring) get some agricultural lime, potassium sulfate, and gypsum. (These are all very inexpensive.) For every 100 sq feet apply 1 quart each of lime and gypsum, and 1/3 cup of potassium sulfate. If you don't mind spending more, use Oyster Shell flour instead of the lime. It releases faster and adds in additional ocean minerals.
2. Dig this into about 10 inches of the clay.
3. Can you find a source of composted leaves & tree trimmings? Some municipalities make this available. If you don't have that, then try Craig's List for an inexpensive bulk source. Spread several inches on top of the clay.
4. Make a deal with your local coffee house to pick up their used grounds for several days. Put a couple inches on top of the leaves / chipped wood. Use a hoe or rake to work this in to the top three inches of soil. You are going to let this compost on the top of the soil. Every few weeks over the summer, get the hoe out and mix it up a bit to work in some oxygen and even things out.
5. In early fall, dig this compost into about 10 inches of the soil. (You now have minerals and hummus mixed in to the clay. No more digging required.)
6. Collect and shred fall leaves. Spread several inches on the top of the bed. Add coffee grounds and hoe in as before. Over winter hoe the top mulch, maybe once a month, just top keep it turned and oxygen moving.
7. Spring - add a complete organic fertilizer and plant!

Do not bury large wood chunks in the soil because firstly that might attract termites. Exposed wood attract termites less than buried wood. Secondly when the micro-organisms are eating at the wood they need nitrogen for protein and reproduction. They will try to get nitrogen from surrounding soil. The larger the wood chunk that is buried, the longer the nitrogen tied-up by micro-organisms.

The single best soil amendment to add to that soil is organic material, compost, shredded leaves, whatever you can find. Do not add any lime, potassium, gypsum, or any similar materials without a good reliable soil test to guide adding those amendments.

Your
University of Illinois Cooperative Extension Service does not do soil testing but they do provide a list of labs that do, http://extension.illinois.edu/soiltest/

kimmq is kimmsr

Raised beds. Keep making and adding compost to the tops of the raised beds.

DEEP-rooted plants, such as okra, that like clay. Cut them off at ground level and leave the roots to decay.

If you want deep roots, daikon in the cool season and sorghum sudangrass in summer take the cake. Or ryegrass, if invasiveness is not an issue. Daikon seed needs to be planted fairly deep, 1 inch or so, and the plant will have maximal root in the soil. Those that are broadcast have more than half the root outside. The taproot will still go 5-7 feet down.

I planted tillage radish in the fall-- they didn't grow well. Can you believe that? My soil was so compacted that TILLAGE RADISH DIDN'T GROW WELL.

Thank you everyone for your ideas. I think my plan is to a) broadfork it for deep penetration (the tines go to 15") b) use a till machine to till in a mixture of compost and half/composted bark chips c) add in blood meal for any nitrogen issues with this plan in addition to sulfur to take down the pH a tad to be nice to my new pagoda dogwoods and then d) hope the worms come to do the rest.

This is my only shot with a big till machine because all the plants are tiny enough to pop out and replant. By next year, hopefully, this won't be an option!

Sounds like you have already taken pH into account which is something I was going to ask about when I saw the recommendation to add lime. If you have the right kind of clay, gypsum can also help - it adds Ca which can help aggregate clay particles into larger structures without raising pH. I am not sure why the earlier poster said that Mg would do this as well and that it was a bad thing.

In any case tons of organic matter will help and you don't need expensive soil conditioners. Get a bulk load of compost delivered. One thing about clay is that you have to keep after it year after year. Once you till in this initial load, add smaller amounts in successive years and taper off on the digging and tilling to allow the spongy structure created by worms and microbes to form and not be destroyed. If there are perennial beds you don't want to disturb after initial tilling, use degradable mulches (leaves, grass clippings) or lay compost down and put wood chips on top. The soil food web will digest and incorporate it.

You can read more about managing clay by searching this forum for 'clay soil'. There are some very informative threads.

Good luck and keep us posted.

take everything you think you know about clay soil.

take everything written in 'garden' magazines about clay soil.

take what most people say about clay soil.

forget it.

it's not about your soil. it's about how you manage it, and that's where most people refuse to learn. so we create this cycle of reinforcement, it must be (bad, crappy, clay, sand) soil.

so let's start at the beginning. your builder gave you a solid foot of this black stuff. we'll figure out what it is later, and that may take some knowledge from local people, but first...where did it come from?

did it come from the lot? did it remain in place during construction, or was it put on top of the construction grade after primary construction was complete?

let's start there, before we assume too much and start supplying answers that may be misleading. I wouldn't even try to guess why radishes wouldn't grow until I knew where the soil came from.

tillage radish have to be planted in August at our latitude to grow well.

I did actually plant them in August.

As far as where the soil came from-- the builder took all the topsoil from the site and stockpiled it. Then they use it to grade each lot after construction. So not only is the dirt itself heavy clay, it was likely compressed in that pile for over year, with lots of anaerobic activity going on-- so not only is it heavy clay, I also think it's sort of...dead. Then during the grading process, it was run over by skid steers over and over again.

This is why I plan to mix more compost in there than I would otherwise-- to bring it back to live in addition to breaking up the clay.

I get it. If you say it is a dead soil, radish may not have grown because radish wants high nutrient levels. You may try another crop that grows on poor compacted soils, (fava is a good candidate, properly inoculated), then inject matter if that fails too.

If you choose to inject matter now, maybe you should consider renting a trencher while the soil is soft, and trench as deep as feasible. It will be too hard a couple of months from now. you can inject any matter you lay your hands on, mixed with the dirt, just add nitrogen if it is too brown.

I agree that lots of organic matter is important. It provides both better soil structure and some nutrients.

To perfect my clay loam and silty clay loam, I added 3 inches of medium and coarse sand and 4 inches of local peat moss. I deeply mixed this all in...instant loose soil. And of course I add organic matter. The sand is a permanent fix and the peatmoss is a long time amendment. The organic matter is a shorter fix to be renewed regularly.

Apparently potatoes break up soil beautifully. You could plant yourself a lovely crop.

If you decide to do that, it is best to purchase seed potatoes which are potatoes that do not have virus. This was highly recommended by my Pests and Diseases teacher way back.

My brother uses his own potatoes, instead of seed potatoes. Doesn't hill them up. Barely waters them. Poor things usually look half head except after rain. And we don't get much rain. He thinks growing potatoes isn't really worth it (gee, I wonder why.) You could grow the most fantastic crop AND improve your soil at the same time.

Lastly, from the little I have read of hugelkultur, it sounds fabulous, AND a good way to get rid of wood.

Best of luck.