If you water the soil first, it's easier to dig, maybe placing a tarp over it watering it every day, or maybe it's baked hard clay and you need to rent a machine to dig it up, maybe jackhammer? Not being a smart alec, really, if the ground is that hardened, it might work. It reminds me of the beginning of the Lasagna gardening books. She couldn't even dig a hole, but after all those layers of cardboard, with layers of clippings 2 feet high, the next year she planted on top of her layering. You might try that.

I've heard some people mix their clay with sand to aerate it, but if you use too little, it makes it twice as hard, so I hope something I mentioned might help. There are a lot of experienced people on this board with clay soil who now have black loam growing they have worked at it so many years.

You need a real he-man tool ( suitable for us ladies too BTW ).

I'm adding a link of the tool I use. It's a pulaski, hoe on one end / ax on the other. Originally developed for firefighters, they are heavy duty, and the weight of the tool gives me that extra power when it hits the dirt. Just be careful and watch your aim. Missing the dirt and smacking your leg really, really hurts. I don't think anybody ever does that twice.

If it's been dry, I water the area ahead of time so it's just damp on the day I plan to dig. Then I get to whacking, build the bed over the top and over time the worms do all the hard work for me. By digging first I can get rid of any tree roots, big chunks of stuff and in theory give the new plants a chance of digging in below the raised bed area.

I find that years down the road, as long as I've continued gardening in the area, the raised bed is no longer necessary. Plus I think useing the clay as the starting base, I end up with really great soil as it holds the nutrients , not letting things leach away. At least that's my theory and it gets me through mentally during the start of new beds.

Good luck and remember to add tons of organic matter, but you know that. It will be beautiful . :)

Here is a link that might be useful: pulaski tool

How deep is your clay?
Duneshot

While it can be done amending clay soils takes time so many people do build raised beds over the clay to get the drainage they need, until eventually the clay does get sufficient quantity of organci matter in that clay. I have simply piled lots of organic matter matter (shredded leaves, compost, etc.) on clay soils and left it sit for some time, months, and found that after a period of time that clay was workable to the point that a spading fork was easily inserted into that clay soil to the top of the tines.

Ditto the comments above ... ammending/taming clay soils is not the work of one season. I sure could have used Plaidbird's PULASKI tool when I was taming my clay soils many years ago.

I have become almost obesessed with the power of roots to dig through my clay soil. [do a google search on key words "Plant Roots" for some very useful info][including interesting video http://www.youtube.com/watch?v=d26AhcKeEbE ]

The link below charts the depth/width of various vegetable roots. My favorite is Swiss Chard ... looks very pretty, while roots go to China. When it goes to seed, the birds love the plant as much as I do. And of course, it is also good to eat. All around perfect clay-busting plant.

BTW ... good luck ... clay soils are the best!

Here is a link that might be useful: Root Development of Vegetable Crops

all our beds are built over clay, i would be suggesting no need to do anything with eh original soil, the worms etc.,. will do that over time, it is the medium you create in which the plants grow, not the original soil.

our clays over here respond to applications of gypsum aspart of amneding, apparently not so over your way by the points put strongly forward by many. you can test to see if clay will respond. take a clump of clay no bigger than golf ball size and place it into a container of water prefferably a jar for 24 hours if the clay begins to dissolve then gypsum should work.

take a look our presentations.

len

Here is a link that might be useful: lens straw bale garden

I agree that you shouldn't disturb the underlying soil, unless you have a plan in place that allows you to control the water that is sure to collect there. Here's why: If you amend the soil beneath your bed water will flow not only downward through your bed, but also laterally into the bowl you've 'created' by amending the very heavy soil and making it more porous. IOW, you will have created the bathtub effect, trapping water that can only dissipate as quickly as the percolation rate of the surrounding soil allows.

This is going to occur anyway, naturally, and soon enough. As soil life 'mixes' the organic matter from above into the clay, you're still going to gradually get this bathtub effect. Do one can think that the soil 15-20-30 ft from your bed will become better-aerated at the same rate the soil beneath your bed will, so even if you leave the bed progress w/o tilling the soil below, within a few years you will still get that bathtub effect. There is no sense in hastening the process by tilling.

As mentioned, if you have a way to mechanically remove the water via a trench/ditch, tile, French drain, or a sump arrangement, it won't matter if you till/amend the soil below the bed. Water will actually dissipate faster from your beds if you don't amend. It will flow laterally across the top of the clay when the clay is saturated. When the top surface is dry, it will percolate into the clay AND move laterally into the dry, upper soil surface faster than it will percolate into surrounding soils out of the bathtub you've created by tilling.

You're caught in a catch 22 situation. While adding OM to the clay should improve tilth/friability, at the same time it creates a water retention basin.

Al

Our community garden is built on clay soil that had heavy equipment parked on it for a couple of years. We put up 12" beds, filled them with a 50/50 sandy loam/compost mix and started planting. We mulched around the beds with bark mulch to help the soil around the beds and keep the weeds down. Five years later you can dig most of the beds at least another foot deep and the plots have grown veggies well as long as their soil is taken care of.

Believe me that clay soil couldn't have been dug up with a jackhammer. It was a dull grey that looked like the lunar surface. Compost and time are great healers.

Where I live there is a nursery chain that sells humic shale ore. If you could get some of that, it will be a huge help with amending the clay soil.

I have clay soil and find that it absorbs organic material at a terrific rate. I suspect that I have been overdoing it with trying to amend all the clay soil as deep as I can. That's probably overkill. So I will be concentrating on just amending the top 2-3" of clay and keeping that covered with mulch.

Here is a link that might be useful: Zamzow's Huma Green humic shale ore

I too would just build over it and let nature do it for you. Most of those crops are not going to need to put roots more than a foot deep anyway, but eventually, they can if they want to.

Re: tools, I have a tool similar to the Pulaski, but mine has a mattock on one end (about 2.5" wide cutting blade like a small and very strong hoe) and instead of an axe on the other, it has a pick. So it's a pick-mattock instead of a pick-axe like the firemen use. The mattock end is great for chopping and breaking dense dry soil, and the pick comes in handy when rocks are encountered for getting around them and pulling them out.

My soil is brick hard, heavy red clay with a thick Bermuda grass lawn. so I wanted to plant in raised beds rather than fighting this soil and invasive grass. I covered the existing sod with 4 layers of cardboard boxes to smother the grass, and put everything on top of that.

In the thread "Reheat old pile in new composter??", I posted a comment "Cold vs Hot Compost" where I explained how I simply piled 6 feet of leaves and grass clippings inside my raised beds last fall and left them all winter. By spring I had a foot of rich leaf mold in the 3 raised beds where I planted herbs, tomatoes, and peppers.

Last week I was removing a few of the determinate tomato vines that were past their prime and replacing them with some suckers I had removed earlier and rooted in pots. The roots of the old plants I was removing were anchored very well into the clay soil beneath the bed. The earthworms, soil microbes, and plant roots together have already begun to improve the tilth of the hard clay beneath the bed. There was no sign of the grass sod or cardboard boxes; the worms had eaten them all up.

Last fall I had originally planned to double dig the area beneath the raised beds, until I found that I could not dig a hole more than a few inches deep. After only 9 months since I piled up the leaves, using only a hand trowel, I was now able to easily dig 6 inches into the original soil beneath the beds. It would have taken a jackhammer to have dug 6 inch last fall.

This fall I'm planning to mix in more leaves to compensate for organic matter that has decayed this summer. As soon as my neighbors rake their leaves and put them by the road, I'm planning to drag them home with me to start a 4th bed for strawberries next spring.

While double digging beds used to be considered the "gold standard" by which to get great results, new research is increasingly going the other way. I was reading a report on the Rodale Institute's website recently about mycorrhizal fungi and its benefits to crops. To maximize mycorrhizal colonization, their research is showing that you should plant cover crops which you mow down rather than turn under. By disturbing the soil as little as possible and keeping cover crops growing whenever fields are not in production, the soil supports development of more beneficial microbes that maintain the tilth of the soil better than plowing does.

I've got a long discussion going about mycorrhizal fungi in the container forum. While soils often contain enough of the fungi so that inoculants are not needed, there has been some debate of whether plants in containers could benefit from inoculation with mycorrhizal fungi. Some said that the high temps in containers would destroy the fungi, but new research suggests the fungi survive the high temps of soil in containers during summer and are a great help to plants in containers during hot weather.

Once you establish a healthy soil climate in the raised beds, recent research suggests that the microbes and plants will take over and do everything that is needed to maintain improve the soil beneath the bed as well.

gtippitt, I am surprised you could kill that Bermuda so effectively. I have chased its roots a foot down and just cannot eradicate it. In my garden it's more like containment or keeping a cancer in remission. It just comes back so all I can do is pull it when I see it and keep it to a minimum. Watch out for bounce-back!

Thanks for all of the excellent experience sharing here!

If you have time, please consider helping out a newbie with a similar situation. You can check out my post here:

http://forums.gardenweb.com/forums/load/ohioval/msg0920035213984.html