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:

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...

Abby

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

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.

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. :-)

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.

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.

http://www.floridabonsaisupplies.com/DE_Bonsai_Soil_Diatomaceus_Earth.html

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

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.

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.

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.

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.

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.

..
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
..

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

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.

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.

Insecticide usage of diatomaceous earth MUST be a fine dust so that it coats all insects with an exoskeleton and dries them up (kills them). However, if you mix it in your potting mix/soil or even dust once and then spray with water, you have pretty much removed any potential Insecticide use. Livestock caretakers must constantly be dusting as any moisture or even other dust that coats the DE will not allow it to stick to and dry out insects. So if you think you are protecting your potting mix/soil from any insects by mixing a dust DE product into your mix, you are throwing your money away (although it is certainly not harmful to anything, plant or insect). It is actually generally NOT used around farms anymore, it is too time consuming. It is still fed to animals because it is both a good calcium supplement and can actually rid several intestinal worms with prolonged usage. Food Grade (NOT feed grade) is great for people to eat also for those same reasons.

The only real distinction of Food Grade is the levels of potentially unwanted metals (think lead). So if you are eating it directly or through a plant you should look for food grade, I believe there is only 1 mine in America that produces Food Grade DE with safe levels of the toxic metals.

Others have pointed out the usage as a soil conditioner and so I won't, but I would say there is really no reason to mix in the fine pesticide powder as it is more expensive and won't provide any pesticide usage if mixed throughout. That being said it is not nearly a "broad spectrum" insecticide as even if you powder coated your entire lawn, the next day after a good dew it is mostly inert and will never be actively hurting insects again unless you re-dust daily.

Some oil-absorbent material for garage cleanup is also the larger particle DE and cheaper than cat litter. Really, any oil-absorbing silica product for garage spill cleanup could likely do the same job as a soil conditioner, so shop around and see what people are using as a ratio, I honestly was looking for the same thing when I found this post. The big thing that may concern some is whether there are potentially unwanted metals in it, and the only sure way to know is if it is specially labeled "Food Grade". For me personally I would consider "Feed Grade" to be fine. Good luck trying to find oil-absorbent or cat litter labeled "Food Grade"!

I thought I should comment, even though I am late to this party, because it is one of the top links in google and yahoo search.

I thought the mechanism of action for insect control was the microscopic sharp edges that cut into their shells, rather than a direct dehydrating action. Maybe the bug loses moisture through all those little cuts and dies of dehydration so it's the same thing.