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nafex - RE: [NAFEX] Clay, long, technical.

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  • From: "Bruce Hansen" <brucehansen@acd.net>
  • To: <nafex@lists.ibiblio.org>
  • Subject: RE: [NAFEX] Clay, long, technical.
  • Date: Tue, 7 Jan 2003 08:36:49 -0500

Joe:

Excellent rap on clay.

Thanks

Bruce

-----Original Message-----
From: nafex-admin@lists.ibiblio.org
[mailto:nafex-admin@lists.ibiblio.org]On Behalf Of Joe and Ellen Hecksel
Sent: Sunday, January 05, 2003 1:50 AM
To: nafex@lists.ibiblio.org
Subject: [NAFEX] Clay, long, technical.




Rodney Eveland wrote:

> I suggest you first find out why the ground is barren. Certain clay like
> soils are barren - period. Bentonite is one of those soils. We have
> outcroppings of it East of here. Mother nature hasn't been able to find
> a plant that will grow in it and I doubt you will either.


Hi Rodney:
Help me out. If memory serves, you are in Wyoming near Sheridan and the
average rainfall is 8" to 10" per year. If so, that might be one of the
factors that exacerbate barren bentonite.

A short chemistry lesson for those who are not familiar with clay
mineralogy: The structure of clay is like a pile of roofing shingles
with ball bearings sprinkled between the layers. The shingles are
sheet-like molecules of LMs-silicates. LMs are light metals (magnesium,
aluminum..., pick one). The ball bearings are very light metal ions
(cations) like sodium or potassium. When dry, the shingles are squished
down tightly and the ball-bearings are insufficient to allow slip
between the shingles. However, the ball bearings keep the shingles far
enough apart that *given time* water molecules can wedge themselves
in-between the shingles. It is a tight fit as the cations are smaller
than the water molecules. The water molecules fluff up the shingles,
lubricate the little ball bearings and make clay as slippery as
whatever. In fact, many clays can hold triple their dry volume in
liquid water.

Clay structure partially explains clay's schizoid behavior around water.
Dry clay repells water because the water molecules have difficulty
prying their way between the shingles, but once there, the shingles are
very reluctant to give them up.

Chemical ammendments like gypsum and limestone displace the sodium and
potassium ions with calcium ions. An ion is an atom stripped of one or
more orbiting electron. Once stripped of the electron, the atom becomes
very reactive or sticky. Calcium ions have two properties. They can
give up either one or two electrons AND they are much larger than sodium
ions. The larger size means the shingles are held farther apart so
water can penetrate much more easily. The fact that they can donate
either one or two electrons means that they can perfectly balance out
the LMs-silicate chemistry and everybody knows that perfectly balanced
machinery can be operated with little effort. That is, very little
energy is required for the water molecules to penetrate between the
shingles.

>Other clays
> have a wonderful reaction with chemicals, especially sulfur or compounds
> that contain sulfur. That's why they sell gypsum to be added to soil.
> Unfortunately some clays have an adverse reaction to these chemicals, so
> you probably should find out if the USDA has a soil scientist in your
> area and then go have a chat with him; other than that horse manure
> sounds pretty good.


Michael Dirr is a horticulturist at U-Georgia who specializes in
landscaping plants. Much of the U-G Athens campus is covered by red
clay (laterite). One planting technique that works well for fussy
plants is to bury half the root ball in the soil and then to mulch to
the top half of the root ball with bark chips. The roots can draw
moisture from the soil and can extract nurients from the 6" layer of
decomposing mulch. One of the things that makes this techique magical
is that the mulch layer can be much lower pH than the clay. The lower
pH of the mulch makes a different set of minerals available. Kind of
like having a hardware store next to a grocery store. Handy.

One of our locally available products is shredded pallets. The pallets
are usually made of oak and I suspect that they are a decent substitute
for bark chips. By the way, the shredded pallets are free.

>Have you or anyone else heard of any benefits from
> barley straw other than as "soil roughage"? When it decays it releases a
> chemical that will keep a small pond algae free and I've heard that
> raspberry production increases when it is used as a mulch, but I've
> never tried it myself.


I am slightly familiar with rye straw suppressing weed growth.

From
http://www.agnr.umd.edu/userforms/nera/Projects/annualrp.cfm?type=NE&numID=1
000

"Rye
Commercially available cultivars of rye (nine in NC and 8 in NY) were
evaluated for their ability to suppress weeds. The rye was planted in
the fall of 1999 and biomass production, allelopathic activity, and weed
suppression in the field were assessed in summer 2000.

Unlike the 1999 results from NC but similar to 1999 results from NY, the
varieties showed no difference in weed suppression in the field. 'Wrens
96' and 'Wrens Abruzzi' produced most biomass in NC, whereas 'Aroostook'
was the most productive in NY and 'Wrens Abruzzi' performed poorly.

An extract bioassay (NC) and a straw bioassay (NY) both showed 'Wheeler'
as having the highest allelopathic activity. In both cases, only certain
test species were affected. Concentrations of DIBOA, an important rye
allelotoxin, were assessed in the NC experiment. By flowering, DIBOA
concentrations were low in all varieties, indicating that allelopathy
demonstrated in the bioassay was due to some other compound(s).

Eleven commercial varieties were planted at MD, NC, NY, and ON in fall
2000 for evaluation in 2001. In addition, 280 rye accessions from the
National Small Grains Collection were planted at NC. The best of these
will be used to initiate a breeding program for cover crop rye.
"


> _______________________________________________


--
-Joe Hecksel
My personal website: http://my.voyager.net/~jhecksel
"We are only here for a short time. So let's make it a good time."
-Cary Dye 1958-2002


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