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leke
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Ground eggshells

Hi, I was wondering if someone could answer some questions about egg shells. I'm currently crushing my egg shells with a mortar grinder and mixing them on the surface of my plants' soil.

1) How long does it take to for the calcium to reach the plants this way?
2) Is there anything else I could do to egg shells to speed up this process?
3) Is there such thing as adding too much shells to the plant soil? If so, how many shells per litre of soil would you recommend?

Any other knowledge is greatly appreciated :)

Thanks.
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rainbowgardener
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Re: Ground eggshells

I don't know the answer to your questions very specifically, but I would assume it is not fast and that eggshells you put in the soil this year, maybe are adding Ca to the soil next year - because you pulverize them. I just put them in my compost pile as is and they are still pretty intact months later. Eventually, like when I am planting with the compost, I hand crunch them a bit and they do disappear after that. My soil isn't full of eggshells. Other that pulverizing (grind to a powder), I don't know of anything you can do to speed up decomposition.

I'm sure you could use pretty many: I saw somewhere that it takes 150 eggshells to make a cup of coarse eggshell powder. The only problems I see with using really large amounts (in case you have hundreds of eggs) is that you would be raising the pH of your soil. It is like a low-key way of liming. If you got to the point where a significant fraction of your soil was eggshell, you would start to be low in other nutrients. I know that calcium and potassium are supposed to stay in balance and having too much calcium can lead to potassium deficiency (well, in people anyway). But all the other nutrients would start to be low in a soil that was largely eggshell, since egg shells have pretty much nothing but calcium.
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applestar
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Re: Ground eggshells

Like rainbowgardener, I just put the cracked open eggshell halves in the compost pile/bin.

If I'm feeling extra industrious, I grind up some eggshells and put them in my vermicompost bin for the worms, but they need them to be powdered I heard or they can get hurt. I sometimes cheat and put entire cracked shells in there, and they manage to slither around or curl up inside the half shell.

When I have Bokashi bin fermenting, I also add crushed (but NOT ground) eggshells.

So I'm not entirely sure how it would work for container plant soil. But I think they would definitely break down faster as ground up powder, and if the container soil is live with microorganisms.

I believe eggshells would also be source of nitrogen and phosphorous. Some sulfur, too.

Another source of calcium would be seashells and shellfish. Again, I just use them as various composting ingredients, but when I find the clam and oyster shells and lobster and crab claws that tend to remain intact in the compost, I put them under (in the bottom of planting hole for) favored plants like paste type tomatoes that need the calcium more.

In Bokashi fermenter, which is an acidic environment, the shells break down faster. I think you could do the same by "pickling" the shells in vinegar, but then you would need to neutralize the acid somehow before giving it to the plants. I wonder what would happen if you put the ground up eggshells in a jar and cover with vinegar? I suppose you could take the result and dilute -- like a spoonful to a bottle of water? I really don't know, but it seems like an idea that could use some experimentation. 8)
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imafan26
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Re: Ground eggshells

I don't know either. It takes a long time, I suspect years. I do not use eggshells in the garden to add calcium, lime is more readily available if you are thinking of changing pH, but even that takes 6 months to accomplish. I use the crushed eggshells and hair in the garden to slow down slugs and snails. I don't know if the eggshells work but hair does.
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rainbowgardener
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Re: Ground eggshells

People say different things about whether egg shells work against slugs / snails or not. I think the difference maybe in the form the shells are in. I have seen people who use the powdered/ pulverized egg shells say very clearly that they do not slow the slugs down and might even encourage them. I do use my slightly hand crushed shells around my plants and I do think they make a difference in helping keep slugs away. Probably sharper.
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toxcrusadr
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Re: Ground eggshells

I put eggshells in my compost for 20 years and used a lot of compost to improve heavy clay. Last year I had the soil analyzed and found that soluble Ca and K were extremely high along with P. I don't know if the eggshells led to high Ca but I have stopped adding eggshells to my compost. Note, my clay is based on degraded limestone so it is a calcium type of clay to begin with. Your situation my be different, which is a good reason to have a soil test done. Not necessarily every year unless you have major issues you're trying to remediate, but if you never had one, this eggshell question is a perfect example of why you should.
Tox

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