THOSE VOLCANIC ROCK POWDERS
The "Dirt Doctor" has been recommending "volcanic rock powders" for amending alkaline clay soils since at least January of 1993. His reasons for doing so have been many and varied. But, at one time or another, he has claimed that "volcanic rock powders" provide plant nutrients and have high cation exchange capacity, water retention capability, and "paramagnetic energy."
As recently as August 19 and 23, 2002, he devoted his two-minute radio spot to extolling the virtues of rocks and rock powders, repeating these claims and saying that any kind of non-native rock would improve the soil, but that "volcanic rocks, like lava sand, granite sand, zeolite, and basalt, are the best." And he added a "free" plug for a product called "Earth's Fortune" (more on this below).
At one time or another in the past, he has also recommended the use of azomite, greensand, schist, diatomaceous earth, and glacial rock powder as "volcanic rock powders."
Laying all claims of potential benefits aside, only 3 of these 9 recommended materials are actually associated with volcanic activity. But, since another one began life as a molten material in the subsurface, we’ll grant him that one, too. That means we will allow lava sand, azomite, granite sand, and basalt to be classed as "volcanic rock powders." But zeolite, greensand, schist, diatomaceous earth, and glacial rock powder are, by no stretch of the imagination, volcanic in origin, so let’s examine each of those -- and have a look at Azomite.
And let's also have a look at IroniteŽ, a falsely maligned gardening product the "Doctor of Dirt" vehemently opposes, and at Earth's FortuneŽ, a newer product he added to his recommended list when it became one of his radio sponsors in September of 2001.
ZEOLITE, commonly used as an absorbent in cat litter and other products, is a large family of secondary minerals composed of hydrated silicates with varying amounts of aluminum, calcium, potassium, and sodium. As any mineralogist can tell you, natural zeolites originate from the post-depositional, chemical alteration of both igneous and sedimentary rocks. Others are man-made and are manufactured from silicate minerals, such as glauconite (greensand).
Curiously, Howard Garrett, the "Dirt Doctor," has said that adding zeolite to a compost heap will prevent nitrogen gas from escaping. Unless he was talking about a sealed bag of artificial, man-made zeolite, he failed to explain how this material, after laying around for thousands, if not millions of years, isn’t already completely saturated with nitrogen. And he didn’t explain where that nitrogen gas was escaping to or why it's escape should be of any concern to us. After all, plain old air is about 78 percent nitrogen.
Of course, this is the same "Dirt Doctor" who said on March 6, 1999, "Zeolite resulted from ash blown out of volcanoes all over Texas." And, on February 10, 2002, he said, "Zeolite was created when volcanoes blew their tops."
Again, in the March, 2002 issue of The Dirt Doctor's Dirt, he confirmed this mistaken belief when he wrote, "Zeolite is a natural volcanic mineral. It contains a wide array of basic minerals that were spewed back to the earth's surface in a cataclysmic event -- a volcanic eruption."
Then, during his radio program on January 4, 2004, he demonstrated both his ignorance and his guile by recommending zeolite to "detox" a soil (whatever that is supposed to mean) containing Osmocote as a fertilizer. He specifically recommended a product that comes from a hot springs location so that "all the calcium and other contaminants have been removed."
GREENSAND is the name geologists give to any marine (ocean) sediment -- sand, silt, or shale -- containing significant amounts of glauconite, a green-colored mineral closely related to micas and clays and essentially a hydrous potassium silicate. Glauconite forms with the chemical alteration of biotite mica in shallow water under reducing (non-oxidizing) conditions, especially in sandstones. Despite these well known geological facts, the "Dirt Doctor" claims, "Greensand is the waste material of small marine animals that lived in the shallow water that used to cover Texas." And he claims that it contains a significant amount of organic matter.
New Jersey greensand has been mined for use as a slow-acting agricultural fertilizer for at least 75 years, with recommended application rates of from 450 to 1,900 lbs. per 1,000 square feet. However, Texas greensand (from both East and South Central Texas) is of such low quality as a fertilizer (University of Texas Bulletin 3232, page 554) that mining it was never commercially feasible until the "Dirt Doctor" began recommending it to gardeners, supposedly because of its iron content. Sadly, the gullible gardeners who purchase this product are not told that almost all of that iron is in the inert, insoluble, ferric form, Fe2O3.
The "Dirt Doctor" claims all the credit for bringing this "new" product to market. Judging from the manner in which he promotes its use, "credit" may not be all he receives from sales of Texas greensand.
Typical of his overdone, even absurd promotion of this product is the statement he made with respect to its use on lawn grass during his call-in radio program August 26, 2000: "Texas greensand will help green things up as fast as anything. Then he added, "There's a lot of organic matter in Texas greensand," a claim he continued to make as late as May 25, 2003, when he added the non sequitur, "Texas greensand has several trace minerals in it and, because of the organic matter in it, they're available right away."
He added to his inanities in the October, 2000, issue of The Dirt Doctor's Dirt, when he wrote, "Texas greensand is one of the best quick green-up agents available. And it builds the health of the soil."
The nutrient most responsible for "greening up" any plant is nitrogen, as most gardeners know. But, since most of the iron in Texas greensand is in an insoluble form, the only active nutrients of any consequence are potassium and magnesium, as the following analysis of a sample of glauconite shows.
Potassium
5.49 %
6.62 % K2O
Sodium
0.27 %
0.36 % Na2O
Magnesium 2.28 %
3.78 % MgO
Aluminum
1.90 %
3.58 % Al2O3
Iron
19.62 %
3.37 % FeO and 24.31 % Fe2O3
Silicon
25.00 %
53.48 %
SiO2
Hydrogen
0.47 %
4.22 % H2O of Hydration
Oxygen
44.97 %
For complete technical descriptions and other information, have a look at Greensand.
SCHIST is a very hard, medium to course-grained, finely banded, metamorphic rock, containing abundant mica minerals. It results from the alteration of igneous and sedimentary rocks by heat and pressure. (Slate and marble are other common metamorphic rocks.)
DIATOMACEOUS EARTH is a salt water or fresh water deposit of the silicon dioxide exoskeletons (frustules) of golden algae, known as diatoms.
(For general interest and information, the algae bloom responsible for large fish kills during recent summers in an increasing number of lakes in north and west central Texas is a golden algae; that is, a diatom.)
The "Dirt Doctor" seems to be aware of the origin of DE most of the time. But, occasionally, he claims that diatomaceous earth is a volcanic dust. And, almost as ludicrous, he has said that the limestone chalk comprising the white cliffs of Dover is diatomaceous earth. For more detailed information on this subject, visit DE and the Dirt Doc.)
GLACIAL ROCK POWDER is a product not normally sold in north central Texas -- fortunately. It comes from the San Gabriel Mountains of California and is essentially limestone scrapings or rubble left behind by melting glaciers. Andrew Lopez, the self-titled "Invisible Gardener" and the Pacific Palisades version of the "Dirt Doctor," is fond of this product and may well be the guru Howard Garrett got his idea from.
AZOMITE is indeed of volcanic origin and is, therefore, a "volcanic rock powder." But it's worthy of discussion for other reasons.
Azomite is a made-up name (A to Z Of Minerals Including Trace Elements) given by a man named Rollin Anderson to a large deposit of smectite (montmorillonite) clay located south of Salt Lake City, Utah. As named and promoted by Anderson, this is a volcanic ash that just so happens to be the same clay mineral -- from the same type of source -- as the clay which permeates the soils of the Texas Blackland Prairie.
No informed person would ever recommend adding azomite to these clay-based soils. But the "Dirt Doctor" did. His reasons for doing so -- and the original, absurd, even laughable claims made in behalf of azomite -- can be found in Chapter 17 of the self-described New Age book, Secrets of the Soil, by Peter Thompkins and Christopher Bird (Harper & Row, 1989). (This book is now available from Acres USA.)
More recently, Peak Minerals--Azomite, of Branson, Missouri, obtained mining rights to the Rollin Anderson site and are selling azomite for use as a fertilizer and as an anti-caking agent for animal feed. As a fertilizer, they recommend using 100 to 600 lbs/acre on the farm and 1 to 2 lbs/10 sq. ft. in the garden. Notice the discrepancy. The garden rate translates to 4,356 to 8,712 lbs/acre. And the farm rate translates to only 0.023 to 0.138 lbs/10 sq. ft. Why in the world would there be such a difference? Unless, maybe, somebody flunked arithmetic in elementary school.
This azomite product is something they (Peak Minerals) label as a hydrated sodium calcium aluminosilicate "formed from the dust of a volcano." As such, it would appear to be the same smectite clay as before. But then they describe their product as a "rhyolitic tuff breccia" and say that it is sold as a "very dusty, fine, free-floating powder" that has a specific gravity of 0.75 and is less than one percent soluble in water. (This can all be viewed at their website, and I especially invite my geologist friends to have a look.)
For non-geologists, here is a translation of the rock description in the previous paragraph. Rhyolite is, by definition, basically the same mixture of minerals as granite but with grains or crystals too small to be seen with the naked eye. Tuff is compacted volcanic fragments (rhyolite fragments, in this case, I suppose) that are very small, generally less than 4 mm (about 1/6th of an inch) in size. And breccia is a conglomeration of sharp-edged, pebble-size or larger rocks (tuff, in this case, I suppose).
These descriptions just don't hang together, especially considering that they also label azomite simply as an aluminosilicate. And the chemical equation they give for it on their website is, more or less, that of a smectite clay, the same mineral as the original azomite. Oh, well. You've got to keep an escape route handy if you're going to stay in the snake oil business for very long.
* * * *
Finally, since the clay in the soils of the Texas Blackland Prairie began life as volcanic ash, the "Dirt Doctor" really should explain why he consistently and continually recommends adding even more of these so-called "volcanic rock powders."
* * * *
IRONITEŽ is a commercial product that consists, basically, of soluble iron sulfate, plus a little added nitrogen. The "Dirt Doctor" had the following to say about it on his radio program of June 17, 2001.
"Ironite is a product I don't recommend," he said, "because it has awfully high levels of arsenic and lead. The Ironite people say they aren't available because they're in the galena form. But, if that's the case, the iron isn't available either."
It is true that IroniteŽ contains galena, which is lead sulfide (PbS). It also contains arsenic, not as galena, but in the form of arsenopyrite (ferro-arsenic sulfide, FeAsS) encapsulated in pyrite (iron sulfide, FeS). Tests conducted by the University of Colorado-Boulder and Inter Ag Services, Inc. showed that IroniteŽ contains these minerals in a concentration of less than one percent. Furthermore, the arsenic had a phytoavailability in a clay soil of 0.00095%; whereas, the native arsenic content of the soil had a phytoavailability of 0.026%, more than 27 times as great. ("Phytoavailability" means "availability to plants.")
According to Will Humble, office chief for the Arizona Department of Health Services, "The results of our risk assessment report found that prolonged use of IroniteŽ does not represent a health risk to residents when applied as recommended on the label." Furthermore, according to the U. S. Environmental Protection Agency and State of Washington LD50 testing methods in which the prescribed maximum dose of IroniteŽ was fed to laboratory rats, IroniteŽ is not considered toxic if accidentally ingested. As a matter of fact, IroniteŽ was found to be safer than common table salt in that regard.
Of course, this might all be considered irrelevant when it's remembered that the "Dirt Doctor" strongly recommends the use of compost because "it contains all 92 mineral elements." And that must certainly include arsenic and lead, as well as cadmium, chromium, copper, plutonium, uranium, etc., etc., etc. (He also recommends a product called Earth's FortuneŽ, as you can see below.)
On the other hand, his statement that if the arsenic and lead in IroniteŽ aren't available then the iron isn't either is simply ignorant and demonstrates once more his continuing lack of knowledge of anything chemical.
And here's something for those gentle visitors who believe that, just because something evil is present, it must be dangerous. The fine crystal goblet you drank that merlot from makes that nice ringing sound because of the lead in the glass. And the pretty green bottle that wonderful Mateus wine rests in has that color because of the combined copper and arsenic in the glass.
And we won't even mention all the gallium arsenide in that cell phone you rub against the side of your head.
EARTH'S FORTUNEŽ
The "Dirt Doctor" began touting this product, formerly known as Nature Gro, on his call-in radio program on Sunday, September 23, 2001, when he welcomed it as a sponsor and described it as a mixture of humus and volcanic ash. (On June 23, 2002, he described it as "half humus and half volcanic rock." Then, on July 28, 2002, he described it as "talcum-powder sized lava sand" and humate.)
But, even though the website for this Farmington, New Mexico, company (www.earthsfortune.com) describes Earth's FortuneŽ as coming "straight from the bellies of ancient volcanoes," it does not specifically mention volcanic ash as a component. It states only that it is "derived from natural volcanic and humate deposits" and specifies that its humates are derived from Leonardite, which is an impure form of lignite coal or shale.
Laying aside any potential benefits for some types of soils, the interesting thing about this product with respect to the "Dirt Doctor" and to the soils of the Texas Blackland Prairie is that he recommends it because he believes that it contains volcanic ash, which "increases the paramagnetism." But volcanic ash is the very material already permeating those alkaline clay soils. So, just as with the AzomiteŽ product discussed earlier, why would anyone want to add even more?
And one must wonder if the "Dirt Doctor" looked at the chemical ingredients of Earth's FortuneŽ, as listed on the "Mineral Content" page of the company website on September 23, 2001. If so, he must have decided that it's okay to sell a product with measurable amounts of arsenic, cadmium, chlorine, chromium, copper, lead, and uranium, provided you're one of his sponsors -- a paying customer, so to speak.
OOPS! Sometime between 9/23/01 and 11/5/01, the Earth's FortuneŽ website was updated, and some improvements were made. On the "How It Works" page, it's no longer claimed that this product is "a micronized powder that plants absorb easily." Now, it says, more accurately, that it's "a micronized powder that is readily available to plant roots and microbes."
On the "Testimonials" page, a statement has been added: "Used and endorsed by the 'Dirt Doctor,' Howard Garrett, and Dave Owens, 'The Garden Guy' (of the Phoenix area)." In addition, a testimonial (well worth reading) has been added from a nursery located in Plano, Texas.
But, most importantly, perhaps, on the "Mineral Content" page, arsenic, cadmium, lead, and uranium have mysteriously disappeared, thereby reducing the number of "Trace Minerals & Nutrients" from 52 to 48. What could possibly have happened to these four elements in that six-week interim? Hmmm. I'm glad I saved -- just for the record -- a hard copy of the original assay.