agricultural lime vs dolomite

joewormMarch 4, 2012

what's the difference?

can either one be used?

does one work faster than the other to raise the PH?

thanks

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tapla (mid-MI z5b-6a)

Aglime can be almost all CaCO3, or it could be roughly the same Ca:Mg ratio that's in prilled garden lime. Prilled lime has lignosulfonate binders to hold the prills together and usually has somewhere around a 2-4:1 Ca:Mg ratio, which is desirable.

The size of the lime particles (along with temperature and soil moisture content) is what determines how fast it works. Prilled limestone is essentially powdered limestone in prilled form, so one would work about as fast as the other - no distinct advantage.

Al

    Bookmark   March 4, 2012 at 10:03PM
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fortyonenorth(6b)

They are both sources of calcium and magnesium. The typical analysis of ag lime is 32% Ca and maybe 1% Mg while dolomite lime is roughly 22% Ca and 11% Mg.

Either can be used to adjust your pH, if that's your goal. However, you'll need to take into account the lack of magnesium if you use ag lime. I generally use ag lime and add magnesium sulfate (epsom salts) as my Mg source. If you're using a fertilizer that contains Mg you can skip the Epsom salts altogether.

Both are relatively fast-acting. However, using pulverized (as opposed to pelletized) lime will be the quicker option. I used to think there was little difference between the two, but I recently read that pulverized lime will raise your substrate pH 1-2 units within a week or so. It will take pelletized lime more than a month to achieve the same increase. The application rate in both cases was 5 lb per cu. yd.

    Bookmark   March 4, 2012 at 10:04PM
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joeworm

went to the feed store, asked for dolomite, made sure he heard DOLOMITE. brought out the bag and loaded it in the car. i didn't pay any attention to what he brought out because I asked for dolomite and he said that's what he had. got home and it is CALCITIC LIME.

went to another feed store and asked for dolomite. he said ok no problem. this time i looked and it is also calcitic. guy said this is what everyone uses.

Is CALCITIC okay or do I need to find dolomite?

Thanks

    Bookmark   March 5, 2012 at 6:02PM
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fortyonenorth(6b)

Yes, you've witnessed first hand the muddle that is lime-type nomenclature. Calcitic lime is high-calcium lime and has roughly the same CCE (calcium carbonate equivalent) as dolomitic lime. In terms of adjusting the pH, they will have roughly the same effect. As I mentioned above, if you use calcitic lime, and if your fertilizer does not contain magnesium, you may want to supplement with a small amount of epsom salts (magnesium sulfate).

I've included a link to a Clemson University site that explains the different types of lime.

Here is a link that might be useful: Clemson

    Bookmark   March 5, 2012 at 9:37PM
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joeworm

can you give me some idea of how much epsom salt to add to the calcitic lime and how best to apply it?

thanks for the help

    Bookmark   March 6, 2012 at 10:15AM
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fortyonenorth(6b)

What are the components/proportions of your container mix and what are you trying to achieve with regard to adjusting the pH? Most bagged mixes already have lime added to adjust pH, so I'm assuming your mixing your own? Maybe something akin to the 5-1-1?

Here is a link that might be useful: Container Soils & Water Movement

    Bookmark   March 6, 2012 at 11:02AM
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joeworm

I haven't done any containers yet but I plan to.

What I'm doing now is making a mix for a raised bed. 1/3 each topsoil, pinebark fines and compost. the topsoil is acid around 5.3 as well as the pine bark so I need to add lime to raise the PH. I have the calcitic lime so I suppose I need to add some magnesium????

Thanks

    Bookmark   March 7, 2012 at 4:57PM
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fortyonenorth(6b)

Magnesium sulfate (epsom salts) is 10 or 11% magnesium. Calcitic lime can be variable, but let's assume it is 70% Ca. If you mix epsom salts to lime 3:1 by weight, the resulting mixture will be roughly 2:1 Ca:Mg - about 17% Ca and 8% Mg, which is a lower analysis than typical dolomitic lime, but you'd just need to add more - about 2x as much, in fact.

Now, having said that, unless you know the Ca and Mg content of your topsoil and compost, I wouldn't automatically add lime. If it were me, and I was building a raised bed, I'd pull a sample for a soil test. Otherwise, you're really just guessing.

Now, if you really want to forego the test, I'd add a cup of your lime per cu. ft. of soil - assuming you're going to thoroughly incorporate the lime. If you are going to just mix it into the top 6" of soil, use half that amount. If you end up getting dolomitic lime (which is a higher analysis) cut those recommendations in half.

    Bookmark   March 7, 2012 at 9:10PM
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