I see that you are in zone three. I'm going to guess that you're in the south somewhere. Because it gets hot and dry, I would recommend keeping your soil covered year-round to prevent the build-up of caliche in the subsoil.

I have a half acre so I'll just work on some raised beds in the ghs. I am going thru it anyway to sift out all of the quack roots. Fortunately I plowed it good last year with the tractor.

idaho_gardner, thanks for the link for caliche. I've always been aware that there was some calcium source that the plants were tapping into. The wild grass and hay looks healthier than other places just a few miles away. So now I am thinking my hardpan is probably doing more good than harm. It no doubt also holds the moisture from soaking down too fast. Mixing some of it with the topsoil when I plow might have the same effect as adding lime.

The sand and gravel below the clay is good in that it lets root grow easily down to the water below. Plants mainly get their nutrients from the warm upper layers and their hot summer water from the deep layers, so you do not need to mix the deep layers of sand and gravel with organic material.

It all comes down to where you want to put the work, into digging through the clay layer and mixing it with lots of organic matter (Composted hardwood chips works wonderfully for this because of its chunky nature) or making raised beds over top. When I prep a new garden area I dig a trench through the clay and then throw in as much raw organic matter in the bottom as I can find (sticks and leaves, plus some fertilizer), mix it in and add more soil. The upper layers get heavy doses of compost and fertilizer.

A good dense cover crop of winter rye will put copious roots into the clay clods when they are mixed into better soil and help break them up further(because the initial digging creates cracks in the clods, which allows access to the roots), but the rots can't do much over top of a solid clay hardpan.

Speaking of raised bed, if you deep dig the garden to 2-3 ft and mix in adequate organic mater you will have raised the soil level by as much as a foot simply by loosening it up.

Humic acid is stabilized and does not feed fungi, it is produced by the action of fungi decomposition of lignin. It will not heol aggregat clay inless the clay is mixed up

As for deep digging, that is similar to the potato farmers in the area going thru right after planting with their subsoilers. I have double dug before I have planted root crops. It's a big job on several 100' rows but it seems to be worth it in a better crop. Although roots over a foot long don't fit in the bag, but if the reach into lower moisture it is a healthier more nutritous root I think.

I've only really skimmed the article but it is reminding me of one of those links (Janong Natural Farming, I think) on the "Why I love the internet" thread, where they show the weeds growning and then smushed down serve as mulch. Or so I thought...

VERY interesting and thanks so much for sharing. Maybe I can view my spurge in a new light. I know I'll really be rethinking the planting of Four O Clocks (though they weren't mentioned) near some roses. Not only for what they're supposed to do for Japanese beetle suppression but also to let the tubers open up some soil nearby.

Not only do I appreciate what can be learned on the internet, I ESPECIALLY appreciate the conversations I can have with folks interested in the same stuff.

I start talking microbes, brews, roots, weeds, plants around my house and eyes start to glaze over or I get interruped with "Oh, look at what the dog is doing now" type comments or "Mom, you are SOOOOOOOO weird."

Many, many thanks..
Penny

This gives the root size of vegetable crops, and it's surprising how extensive they can be.

http://www.soilandhealth.org/01aglibrary/010137veg.roots/010137toc.htm l

I also sow some Elephant Amaranthus [pigweed] in my watermelons...stripping off the lower 3 foot of leaves....I hauled a 45¾ pound watermelon in the wheelbarrow from the garden today [also a 40½ pounder]...just braggin but true. These were from a large growing variety though.

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

While there is no doubt some illuviated clay in the B horizon, the OP's overall description suggests we're looking at glacial or fluvial deposits, so I would guess the clay is the parent material and not illuvial accumulation.