roots compartmentalizing?

[Nickrosis]

Yeah, I think you might be mixing some things together.

There are a couple of things that can be positive and negative in trees and soil. First, arborist attitutudes....

Water potential: This is all about tree-water relations. So you have a root that wants to absorb water. Say there is plenty of water outside the root, so it just flows across a membrane into the root because the root is parched and the soil is soaking. Like a paper towel soaking up water.

This is rarely the case, though. Usually, you have a root that has more water than the soil. The root needs that water to exist, and the soil is often pretty dry, especially later in the season around here. To continue to absorb water, the root has to become more thirsty, in effect. It increases its solute concentration. That makes the root more negative in terms of water potential.

Say the root is -7000 and the soil is -8000. The root has to drop its potential so water is not taken out of the root. So it drops to -9000 and pulls water away from the soil. The more negative it gets, though, the less water is in that area and the more solutes, or absorbed, substances are there.

Now, it gets stressful on the tree. The stem has to drop below -9000 to pull water through it. The leaves have to drop below the stem, etc. So a chloroplast in the leaf needs to be really negative to draw water all the way from the roots.

Big picture: When water is less available around the roots, the leaves can't have as much water in them if they want to continue to pull water up. So they consume it and make sugar or transpire, releasing water through stomates or openings.

 

[Nickrosis]

Now to actually answer your question:

Soil has positive and negative charges in it as well.
Positive charges: hold negative particles
Negative charges: hold positive particles

If a tree wants a positive particle, it has to pull it off of a negative charge in the soil. Metals are positive, like iron or potassium. All these things are called cations, meaning they have positive charges.

Most nutrients, though, are negative and called anions. They are rarely in compounds by themself. Nitrogen, for example, is unavailable as a gas (N2), but it is readily absorbed as nitrate (NO3-), nitrite (NO2-), or ammonium (NH4+)....ok, so that wasn't negative.

Most things work because of charges. Lightning strikes because of charges, lights turn on of course, and trees absorb nutrients and water because of charges.

As far as lightning goes, I don't know. Maybe it gets hit more than once because of a trait in the tree: height, charge, altitude, etc. I don't believe that charging the soil would have a significant impact on a tree and its nutrition. The earth is so big, it absorbs a lot of local changes very well and very quickly. After a lightning strike, all that electrical energy dissipates nearly instantaneously, giving off heat, light, and sound.

Am I getting at anything interesting? Let me know what you're looking for. This is all off the top of my head, so please correct me! If you want to research this further, a plant physiology book and a chemistry handbook would be a great set of resources.

 

[xtremetrees]

Soil is negative charged particles. Cations is kinda like water and postively charged onto soil particles?

In between the soil particles is macropores or space and this is where the roots grow?

So why is clay soil a better medium or CEC cation exchange capacity.

I can see how adding mychoriza fungi into sandy soil is bestter than than clay because there is more froom for roots to grow.Is this right?

 

[Nickrosis]

Originally posted by xtremetrees
Soil is negative charged particles. Cations is kinda like water and postively charged onto soil particles?

I don't know how to answer that....it's probably just my stupidity.

Originally posted by xtremetrees In between the soil particles is macropores or space and this is where the roots grow?

Roots just go through the soil, surrounded by soil and by micro and macropores and by no pores. They do better when there is oxygen, like I was saying before.

Originally posted by xtremetrees
So why is clay soil a better medium or CEC cation exchange capacity.

Clay soil is not the best medium, but it offers the highest CEC (cation exchange capacity). Essentially, clay particles are tiny (<0.0039 mm)...smaller than silt (.0020 to .0074 mm) and far smaller than sand (0.0625 to 2 mm). CEC is based up on the surface area of a particle...the greater the surface area, the greater the area for ions to latch onto. So in a clay soil, you have many more particles with a much higher cumulative surface area. An ounce of clay has enough surface area to cover 243,943 square feet!

Here's a fantastic soil website: http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/soil_systems/title_page.html

Originally posted by xtremetrees
I can see how adding mychoriza fungi into sandy soil is bestter than than clay because there is more froom for roots to grow.Is this right?

I wouldn't feel comfortable saying that. The success and benefit of myccorhizae is based more on many other factors. If there is a healthy population of fungi present, it may have no noticeable impact. If the soil is too dry and inhospitable for the fungi to "take", you may as well urinate there because there's at least water and nitrogen in that!

Hope I'm helping!