Soil and Compost forum: How to add Calcium - lime or what else?

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Farmer
Jun 19, 2016 6:39 AM CST
I just bought a bag of Calcium carbonate and want to know what formula to use to get it into the area I want to use for gardening. Currently all sandy soil weeds and grass grow well,
Do I mix it with water by the gallon ? how many tablespoons to a gallon?
I have planted 15 tomato plants but they are straggly due to poor light but that will change this week I am removing some trees to give me sun to garden.
Name: Sue
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sooby
Jun 19, 2016 6:51 AM CST
Welcome! The amount to use depends on your soil type and the soil pH so we can't answer the question without that info. You should not apply limestone unless a soil test has indicated that it is necessary.
Name: Elaine
South Sarasota, Florida (Zone 9b)
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dyzzypyxxy
Jun 19, 2016 7:39 AM CST
Also, if you could please put your location into your profile, so we know where you are, that will help. Your climatic conditions - humidity, heat in summer, and especially rainfall all have a bearing on what to amend your soil with. Compost, compost, compost is always a great place to start. Adding calcium if your soil is already alkaline could spell a lot of trouble.

It's also a good idea to have the irrigation water you're using tested for pH and soluble solids, too. I use high pH well water to irrigate my garden in the springtime before it gets rainy here. That well water raises the pH of the soil over time so that some of my plants show the stress. As soon as it starts to rain generously, that corrects itself, thankfully.
Elaine

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Farmer
Jun 19, 2016 2:24 PM CST
I had a test done it is low in calcium
Name: Elaine
South Sarasota, Florida (Zone 9b)
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dyzzypyxxy
Jun 19, 2016 3:13 PM CST
Need more detailed info than that, I'm afraid.
Elaine

"Success is stumbling from failure to failure with no loss of enthusiasm." –Winston Churchill
Name: stone
near Macon Georgia (USA) (Zone 8a)
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stone
Jun 20, 2016 7:45 AM CST
Also.... If you are anywhere near me... Cutting down the trees could escalate your problems... That hot subtropical sun... at my house in the Sandhills... My cukes are being sun scalded... Some years, it's the tomatoes being sun scalded...

I don't know how to use the product you have either... But when I'm trying to improve the soil, I bring in organic amendments, and let the acidity of the soil and trace mineral issues resolve themselves.

Personally.... I know where all the horses are boarded in my area... And.... I pull up with my pick-em-up-truck.... And haul away all the poop I can carry. Really important to get a LOT of organic material into that dry sand.
Name: Rick Corey
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RickCorey
Jun 20, 2016 7:52 PM CST
With lime, usually all you have to do is spread it on the surface. Rain will carry it down, and if it doesn't, that's good, because then the lime will dissolve slower and benefit the soil longer.

In some areas, the soil is "always" acid, and "everyone" has to add a layer of lime every few years. Clerks in feed stores should know that "local soil is usually acid", or anyone connected with farming. Not knowing where you live, I can't guess at your soil or climate. If the "feed store" has rows of pallets of lime, your area usually needs lime!

Calcium carbonate is a form of lime, but I'm used to using "dolomite lime" that has MgCO3 as well as CaCO3. Where I lived, Magnesium was "always needed".

I think the problem some people have referred to is that lime or CaCO3 is going to make your soil more basic (less acid).

If the soil is acid and NEEDS its pH raised that way, fine and good.

Once you know the actual pH of your soil, you can apply the rule of thumb that "sandy soil has very little buffering capacity for pH changes" and add the LEAST amount of lime that will counteract your soil's excessive acidity.

BUT, the problem is that if your soil's pH is on the basic side already (widespread in many parts of the country), adding lime will make it worse, and bad pH is very bad. Worse than having low levels of a micro-nutrient.

If you add more CaCO3 than your sand wants, it could possibly push the pH as high as pH 9.4 (VERY basic). I don't think many plants tolerate pH above 7.7 or 8, but I never had to look that up. I aim for 6.5 to 7.0 (very slightly acid).

If you don't have a soil pH measurement and don't want to buy a kit to check it yourself, use very little lime (or none).

Did they calculate how much you need to add to supply the missing Ca? Start with half or 1/4 that much, and only apply it to one small part of your garden, where you don't mind killing plants and making the soil too basic. Each year the plants in that area DON'T die, you'll know it's safe to add that much to the rest of your garden. When the test area starts dieing, that was too much lime. With very sandy soil, it might recover through water flushing the soil and dissolving excess lime. Or stop liming the rest of the bed and mix the over-limed spot with everything else, and hope the average pH is OK.

But the "rule" of conventional wisdom says:
Never add a nutrient unless you KNOW it is needed.
Slight excess is usually worse than a substantial lack.


You probably need some Ca, which is halfway between a macro-nutrient and a micro-nutrient.
You might not need very much, in terms of pounds per acre or grams per 10 square yards.
Hopefully that amount is much less than will poison your soil with high pH.

But applying lime to basic soil would very bad for any plants you tried to grow there.

If your soil is on the acid side for what you want to grow, charge ahead adding lime per the pH recommendations.
But if you don't know the soil pH, or it is OK, basic, or slightly basic, avoid adding lime. Sandy soil has very little buffering action and you might wind up with =sand that is too basic to grow anything.

How about gypsum, hydrated calcium sulfate? That should be fairly close to pH-neutral, but add Ca and SO4.

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