I have often thought about that. Perhaps the root nestles deeper when the ground heaves up and down due to frost but I have no proof of that.
I would suspect the new decomposing leaf litter deposited each year accounts for the majority of new surface soil. So in essence the top of the root (not the neck) stays at the same level and the soil builds up on top of the root over the years. So we know the root grows down and the neck grows up but the top of the root is ground zero. If those twigs, sticks and 3 to 6 inches or more of annual leaf litter decompose down to 1/4 inch of new soil each year, than every 4 years the forest would be adding an additional inch of soil to the surface.
So a 16 year old root could be 4 inches deep with a 2 to 3 inch neck. That seems about right.
I know the new growth bud at the top of the neck is typically 1 and sometimes 2 inches or more below the surface of the soil. This is mother nature protecting the new growth bud. Also that 1 to 2 inches of soil above the growth bud helps secure and stabilize the plant stalk once it grows. Without that 2 inches of soil the heavy plant top will topple over and lay on the ground. I am sure everyone has seen ginseng growing in loose loamy sandy soil and the plant lays sideways on the ground. Sometimes this type of loose soil will not support the stalk. They seems to grow just fine thou when this happens.
I know you fellas already know this stuff, I just throw it in if anyone new to ginseng is reading and wants to hear more.
Getting ready to go clear some future planting beds today for next fall. Many Japanese Honeysuckle need to be pulled up and I need to get into the woods for my weekly fix.
Guy, I won't say that I know the answer to this for sure, but it seems to me that the root somehow digs itself deeper into the ground. I have thought along the lines of Latt's explanation, but that theory does not account for wild plants that I've found on very steep areas with little to no topsoil and still have to dig down 2-3 inches to get to the top of the neck and then 2-3 more inches to the main root. Also if you plant a seed just one inch deep how come you would have to dig down 2 1/2-3 inches deep just a few years later to get to the main root? In my mind the only logical explanation is that the root somehow works itself deeper into the ground.
I think it's a combination of all of the above statements. The long feeder roots anchor and pull downward giving the main root the wrinkles and stress look.
I dug a root 3 years ago and thought I'd never get to the bud,about 6 inches. Then another 6 inches to the top of the root. I had a hole dug out the size of a wash tub. That's the reason I dig with a mattock instead of smaller implements. And oh yes, it was a nice 4 prong with a monster old wrinkled root.
It certainly does seem it may work itself downward some how. I had thought about it too pertaining to roots growing on a steep gully with erosion. How does this root get deeper on that steep hillside without the addition of the annual leaf litter compost accumulating to add soil to the surface.
Rootman, it must be a combination as you had mentioned.
I posted this last year in regards to a \"long necked root\" that TNhunter dug.
Have you ever wondered how a root can keep extending it neck upward each year without it protruding above the soil? I know I have.
Here is some info I found in a book called: Ginseng, How to find, grow, and use Americas Forest Gold. By Kim Derek Pritts.
\"The Koreans theorize that the ginseng root contracts in september or october of each year and actually \"wriggles\" deeper into the soil to accommodate the upward growth of the neck. The yearly shrinking of the root keeps the bud stem underground and helps to produce the valuable circles or transverse wrinkles around the root. The theory would seem to have merit, because the neck of the ginseng root rarely protrudes above the soil surface, no matter how elongated it has become.\"