diatomaceous earth- what can it do?

phantom_white(6)March 13, 2012

I'm a distributor for food grade diatomaceous earth and have read it can be used as a soil conditioner. I can get the stuff (pure DE, not some DE with fillers) at a decent price and was wondering if it could have any good effects on my red clay soil. If so, any idea how much I'd need to use? My garden is about 70x30.


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rhizo_1 (North AL) zone 7

Food grade DE is not used as a soil conditioner, it is not recommended that you do so. A much coarser grade of DE is used as the soil conditioner (see attached image).

Food grade DE is used, as I am sure that you know, as a pesticide. It should be used with caution in the garden. It is almost dust like in particle size.

Here is a link that might be useful:

    Bookmark   March 13, 2012 at 10:43PM
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So why isn't food grade DE okay for the garden? I know the particles are very fine and I use it to kill potato, cuke, and bean beetles. I've never have trouble with it otherwise...


    Bookmark   March 14, 2012 at 5:24PM
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Timely thread as I bought a large bag of food grade DE when I was on a trip a month ago as I cannot get it in quantity locally. I've used non-food-grade DE for years for ants altho have also heard it's effective for bed bugs. Fortunately haven't had those but am concerned every time I stay in a hotel. Recently also read it's "very effective in breaking up hard pan, conditioning heavy clay soils" - link posted below.

All the info I've read online say that food grade DE is OK as a soil conditioner.

I'm not sure how much to apply to my soil so hope someone else knows.

Here is a link that might be useful: diatomaceous earth info

    Bookmark   March 14, 2012 at 10:43PM
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rhizo_1 (North AL) zone 7

You would extremely disappointed using food grade DE as a soil conditioner; the particles are simply too small. The larger stuff is much easier to find than it used to be. I commonly see it recommended as a potting soil amendment. In the past, this particular product was something of a well kept secret in the sports field maintenance arena, often use to amend/build ball fields and golf greens. It is also popular in bonsai culture. The very small particle size would be utterly useless for any of those purposes.

The reason that food/horticultural grade DE should not be used in large amounts in the garden or in garden soil is simply because it is a broad spectrum pesticide. All such products need to be used responsibly and with care and planning. We don't think of it as being broad spectrum, but it is.

I keep some on hand, however, to use in my containers to control foraging ants, millipedes, or other critters that may want to take up residence in the potting soil. I also use it in the nook and crannies of my garage and storage shed to help with the abundance of black widow spiders.

    Bookmark   March 14, 2012 at 11:10PM
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Rhizo, how do you use it in your containers? Do you mix it with the soil and how much do you use? Thanks for any help you can give. :-)

    Bookmark   March 15, 2012 at 10:33PM
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Most everything I can find about using Diatomaceous Earth as a soil conditioner is put out there by people with a vested interest is selling you the product. So then comes the question "what does DE do to condition soil?"
Since a major problem with sand is the large pore spaces DE is not going to help fill those and will not improve moisture and nutrient retention in those sandy soils. DE in sand then is a large waster of money.
Since a major problem in clay soils is the soil particles tend to stick together too tightly and clay soils need something to seperate those particles so moisture and nutrients can be moved about and plant roots can do that too. Most every university I have found that has an article about adding sand to clay to "open" that clay up will tell you that you need between 45 and 75 percent sand to accomplish that and since DE is very similar to sand I would suspect you would need that much DE, also. Therefore, getting enough DE to make a difference in your clay soil will be very expensive.
Keep the DE for insect control and forget soil conditioning.

    Bookmark   March 16, 2012 at 7:19AM
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rhizo_1 (North AL) zone 7

Kimmsr, you are confusing the issue. We are talking about two entirely different products. Or....at least I am TRYING to differentiate between food/horticultural grade DE and the calcined DE granules that have been used to condition soils for many years. That you suggest it may have similar properties to sand certainly indicates that you are uninformed about the physical properties of calcined DE and likely have never heard of it nor seen it. I will be most happy to supply you with some information about it.

It is a remarkably porous and durable granule, with an extensive surface area and internal structure that not only improves drainage, oxygen access and gas exchange in a soil (or medium), but offers a very high CEC (cation exchange capacity), as well. Let's call it 'Amendment Grade DE'. It is a large particle, about the size of BBs.


luckygal, you understand that I recommend food/horticultural grade DE for use in containers only to help control the unwanted soil critters that seem to love my bark based medium. Very little goes a long way for this purpose. More often than not, I simply sprinkle a layer on the surface of the medium, knowing that most anything in there is going to wander around up there at some point.

I have added it to the potting mix in advance, for those containers that I know from experience will become fire ant havens. I can't say for sure how much, but probably as much as a cup per twenty inch pot. Wear gloves when doing this so that your hands don't get irritated.

Here is a link that might be useful: Information on Amendment Grade DE

    Bookmark   March 16, 2012 at 12:41PM
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rhizo_1 is correct. Calcined DE soil amendments are excellent for both sandy soils and clay soils. In sandy soils, the DE particles absorb water that would otherwise just run through the sand, and make it available to the plants. This is why many golf courses use it in their sand-based greens and tees.

In clay soils, DE soil amendments provide needed porosity for both air and water to penetrate the root zone.

As a general rule of thumb, about 10% by volume blended into the root zone or potting soil is sufficient. More can be used for container or rooftop gardens and harsher conditions.

I work for EP Minerals, the manufacturer of 'Axis' DE soil amendments. This isn't a sales pitch, but actual personal experience, backed up by scientific data. Feel free to look us up and read about our soil amendment products.

We also produce the food-grade DE powders that are used as insecticides, but these are different from the soil amendments. You can also blend these powders into soil and it will help some, but it is not as effective as the calcined granules made specifically for this purpose.

Here is a link that might be useful: EP Minerals -- producer of Axis DE soil amendments and other DE products.

    Bookmark   March 16, 2012 at 7:40PM
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rhizo_1 (North AL) zone 7

Now it DOES sound like a sales pitch and that I was in on it! I wouldn't do that to you all, nor to Gardenweb.

    Bookmark   March 17, 2012 at 5:23PM
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Is there a specific brand that's food-grade? I'd like to use it to get rid of all the ants we have in Pennsylvania, but I'm concerned about our German Shepherd Dog. I don't want him to ingest something that would hurt him.

    Bookmark   April 25, 2012 at 7:14AM
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You can get the larger particle stuff as cat litter. Lots of people using cat litter as seed starter. Just be sure you don't get clay litter.

    Bookmark   April 25, 2012 at 12:24PM
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toxcrusadr Clay Soil(Zone 6a - MO)

Thanks for the explanation rhizo. I did not know about the calcined form and was thinking along the same lines as kimmsr until you explained it.

    Bookmark   April 25, 2012 at 5:06PM
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Where does the food grade part come in in food grade Diatomaceous Earth? How is it used in food?

Yahoo just returned a bunch of adds except for a wikipedia account that didn't really address the food grade part.

thanks in advance

    Bookmark   April 26, 2012 at 2:03AM
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rhizo_1 (North AL) zone 7

Food grade DE is used in grain storage (for all grains, flours, etc.) You eat it every day, most likely. It is also used for poultry, livestock and even pets, to help with internal and external parasites and pests. It's in our animal feed, since that is mostly grain based, these days.

Any good Feed and Seed type of dealer will sell large bags of food grade DE, as it is not only added to their food but can be dusted in the nesting areas, stalls, etc.

If you enter a few of the websites of the on line sellers of DE, you can become somewhat educated. Even the web site linked earlier from EP minerals has some good information.

Here is a link that might be useful: Click here

    Bookmark   April 26, 2012 at 1:31PM
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toxcrusadr Clay Soil(Zone 6a - MO)

I think rott was asking what it's good for in food, and I'm curious about that too.

Does it deter insects from eating the grain?

It's just silica, so it has no nutritional benefit.

    Bookmark   April 30, 2012 at 12:52PM
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Hi I used to be a bonsai gardener. and in bonsai a form of diatomaceous earth is required for a proper soil mix for bonsai. This is traditionally akadama a Japanese fired clay its very expensive and there are alternatives. Some people use cat litter others use turface. my favorite alternative is Napa floor dry or part #8822 its cheap and works costs about 8 dollars a bag. The use of diatomaceous earth helps with soil drainage air circulation and growth control. Some people use as much as 100% floor dry. I don't recommend this because bonsai growers want complete control over there plant growth. I would use about 50 percent or 35 percent for soil mixes. because its not organic and won't have nutritional properties for your plant. Hope I helped.

    Bookmark   April 26, 2014 at 7:21PM
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