that observation begs a follow up question or two.

Deep or wide plantinng area?

How deep/wide should I make my soon to be new raised beds?

The nnew roots 0-3" below ground were all huge and numerous.

The plants developed roots all along the buried stem, but the roots below 3" were sparse and quite tiny.

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You might be interested in what I linked to below as regards root structure of tomatoes. The roots go down much further than you saw and it's the tiny ones, and most get broken off when you lift the plant, that make up the fibrous root structure that is so important in water and nutrient uptake.

I trench plants only when they're too big to plant vertically.

You'll notice from that chapter on tomato root structure that direct seed plants that are never transplanted as small plants develop tap roots while those that are transplanted at the one to two leaf stage develop a fibrous root structure which is desired.

Carolyn

Here is a link that might be useful: Tomato Root Structure

Carolyn137, I read that article a while back & direct sowed the seed to get the taproot as we live in a desert here & I wanted as deep as possible rooting. I also did some transplants. Both ways worked well.

Thanks for the link carolyn.

One problem. Either I did not post enough information in my original post, or I do not understand the PDF supplied.

Is this correct?
Transplanting wipes out the tap root more or less.
For most tomato growers, this ends up as a good thing
because a more fibrous root structure is the result.
Fibrous roots are important for water and nutrient uptake.

My plants were transplanted many times before heading out into the cold dark world.
At the end of season, I did not pull the tomatoes out. I dug a circle arround them about 3" out then shook off the dirt.

They had two of the root balls like in the first picture, on the left of this webpage.
http://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch26.html

The original ?fibrous? root ball was there deep, and another ?fibrous? root ball at the surface. Between the two root balls
was an occasional, tiny root coming out. Not quite the
mass of roots I was expecting up and down the entire system.
I wish I could find my camera.. sigh.

I was expecting it to be a mass of roots all the way up and down.

I doubt water was a problem.
It was fresh, warmish, topsoil but maybe not war enough. Oxygen?

Adding:
since the second rootball is only at the surface,
if I trench them shallow, I'm thinking I will get one massive
fibrous rootball instead of 2 smaller.

My thoughts after all these years is that few things are just absolute and in black and white. There are usually mitigating and extenuating circumstances to things. Consequently, I think that if one only has shallow soil, or a shallow layer of fertile soil that holds moisture, a shallow, fiberous root system would be best and the more the better. I think that most plants are opportunistic and tend to take advantage of what opportunities are afforded to them as best they can.

The Excellent study on plant roots that Carolyn posted the link to is what plants will most likely try to do given decent circumstances, but that is not always possible for them.

I have been composting, amending and building my soil for a number of years and the clay beneath the original 8 to 12 inches of sandy loam topsoil has been improved to a dark, rich material that is softer and much easier to work. I am convinced that it holds nutrients and moisture much better than the top and more loose topsoil. I also think that it allows the plant roots to dive deep if they want to.

I mulch heavily with shredded oak leaves and water with soak hoses under those leaves, so I have adapted to keeping plants going through our all too common droughts and hot weather, but am of the opinion that if that were not possible, the plants with the deep roots would fare far better than any with shallow roots. It also does not take frewuent waterings and applications of plant food or fertilizer.

I have tried a bit of trenching when I had plants that had become too leggy, but have not been able to note any significant difference in them and the others planted in the normal way, other than wilting sooner and needing more frequent waterings.
Thant is just my observations from my garden, under my circumstances.
Bill P.

I like to take advantage of both principles of deep roots and new stem roots by using a diagonal trench. This allows the football to start nice and deep for moisture and additional feeder roots to form near the surface.
In reality though I think it is more of a ceremony than a necessity. My ceremony includes way to much preparation and adding a bit of soft rock phosphate directly under each seedling, but that's fun to me)

I think we could all get away with using a hoe to open up a hole drop a seedling in and cover with loose dirt leaving some leaves above and move on and water in later and still have success. These plants are adaptive. given aproipriate fertility and conditions they thrive.

interesting points re: deep root + water.

hmmm... I am unconverted, but will experiment this year.

Last summer I snapped off a rather large sucker from a beefmaster plant and jammed it into the ground with no prep whatsoever. Then poured a little fish/seaweed mix around it and forgot it. A week later it had perked up and looked quite healthy. Soon it was flowering and before long fruiting. Got some huge tomatoes from that orphan. One tough plant!

How deep the roots grow is also a function of how they receive water.

Deeper planted rootballs in a study done in the south showed that the cooler rootball influenced more fruit set in higher temps.