calcitic vs. dolomitic lime

west9491(6)March 19, 2008

due to my soil test, i need lime and calcium (see the thread..)

anyway, someone there recommended calcitic lime to cover both of these issues, i went to walmart and they sell dolomitic, it says it has, i think, 17% calcium?

1. whats the calcium pct. in calcitic lime?

2. will dolomitic lime be just as helpful, or should i got get calcitic?

oh yeah and...

3. most of us put this on top of our lawns, etc.

how far does this stuff work down into the soil? Does it penetrate as much as water does since it dissolves?

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Well, you can get so-called agricultural lime which is calcium carbonate. Very alkaline and contains loads of calcium.
You can also get dolomite lime, which contains varying proportions of both calcium carbonate and magnesium carbonate. Also very alkaline but contains magnesium as well as calcium.
I use dolomite lime because PNW soils tend to be leached out of both calcium and magnesium.
Percentages of active ingredients vary and should be marked on any package you purchase.
Personally, I would recommend getting a product called Dolopril. This is dolomite lime in a granularized medium. It's much easier to accurately broadcast and doesn't blow with the wind or go up in great drifting clouds when you try to spread it.
That's about all I know.

    Bookmark   March 19, 2008 at 11:54AM
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Lime is Calcium, Calcium Carbonate. Calcitic lime is just Calcium, CACO3. Dolomitic lime is Calcium and Magnesium, CaMg(Co3)2. If your soil is in need of Magnesium then you need to apply dolomitic lime, but if the soil test indicates ample reserves of Magnesium but insufficeint reserves of Calcium what you need is calcitic lime.
Lime slowly reacts in soil unless you get hydrated lime which is why the best time to apply lime on your soil is in the fall. Applying in the spring will not harm anything but there will not be much change in soil pH for several months.

    Bookmark   March 19, 2008 at 12:49PM
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PaulNS(NS zone 6a)

Our soil tested medium-high for magnesium, low for calcium, so we went hunting everywhere for calcitic lime. None of the hardware/nursery places carried it, but we did discover there's a limestone mine about an hour and a half's drive from home. We took a detour there on a drive to town one day and they let us load the truck with half a dozen bags for free - a small quantity to them, and they were happy to know it would be put to good use in a garden. So, you might try checking around for sources.

    Bookmark   March 19, 2008 at 1:06PM
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"Calcitic lime is just Calcium, CACO3"
CaCO3 is calcium carbonate; a liming material and the one most commonly referred to as just plain 'lime'. Calcium alone is an element: "Ca". Whereas calcium carbonate is CaCO3: one calcium, one carbon and three oxygens (calcium:'Ca' carbonate'CO3').
"Lime is Calcium, Calcium Carbonate"
If you dropped the first 'calcium' in that statement, you would be correct for most practical purposes:
"Lime is calcium carbonate". or "Calcium carbonate is a type of lime."
Calcium alone is not 'CaCO3'. However, there are many types of lime such as calcium carbonate which is CaCO3, hydrated lime which is Ca(OH)2, Burned lime which is CaO, Dolomite lime which is CaCO3*MgCO3, and more.
But everything that contains calcium is not lime, and calcium alone is not lime.

    Bookmark   March 19, 2008 at 1:35PM
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my Mg was like 252, it said it was high on the test. So don't think i need dolomitic, or does it really matter that it would go higher?

    Bookmark   March 19, 2008 at 6:31PM
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Yes. More Magnesium can cause you problems because it can interfere with the uptake of other, needed nutrients plants growing in that soil resulting in plants in stress that are more attractive to insect pests. Balance is what is needed.
Getting too in depth when explaining things can result in many people not understanding the basics, the principle that should be used is Keep It Simple.

    Bookmark   March 20, 2008 at 7:21AM
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Getting too in depth when explaining things can result in many people not understanding the basics, the principle that should be used is Keep It Simple.
You're absolutely right.
Fortunately or unfortunately, a forum that revolves around soil revolves around chemistry, which can be a complicated subject.
But I do recognize that there should be a balance somewhere among completeness, accuracy and simplicity.
In an effort to simplify my last post I offer the following:
What I was trying to illustrate was that calcium is not CaCO3 because CaCO3 is calcium carbonate. Calcium carbonate changes pH. Calcium does not.
If someone believes that CaCO3 is calcium, they will likely believe that adding "calcium" or any product containing calcium,will raise the pH. It's simply not true. Calcium is only one component of calcium carbonate and it is not the component that effects pH. When someone says "lime" they are probably talking about calcium carbonate, but without knowing for sure, there are a host of other products that may be referring to.

And yes, I too would say to stick with calcitic lime. I agree that you shouldn't add Mg if you don't need it.

    Bookmark   March 20, 2008 at 9:54AM
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cool, thanks for you people, helping...people...

    Bookmark   March 20, 2008 at 8:09PM
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The dolomite lime I use (when I use dolomite) is 20%Ca and 11%Mg. This is far too high in Magnesium to use unless your soil is very low in Mg. The ideal soil Ca/Mg balance is 7 parts Ca to 1 part Mg by weight, not 2:1 as in the dolomite.

Agricultural "sweet" lime is around 39% Ca and 2% Mg. I often use a mix of the two if I'm adding lime to potting soil, 2 parts ag lime to 1 part dolomite will give you close to that ideal 7:1 ratio.

High Magnesium makes the soil tighter, allows less air in the soil, and leads to poor biological activity and slow breakdown of organic matter. If a green crop turned down it the fall is still green when you till in the spring, chances are your Mg level is way too high.

Due to various factors, among them lack of knowledge by OG Magazine founder JI Rodale, many organic gardeners only use dolomite, and many garden centers only sell dolomite. It is generally a bad idea, unless you have a very loose sandy soil and want to tighten it up; even then the Ca/Mg ratio should not be less than 5:1.

The higher the Calcium the looser the soil; the higher the Magnesium the tighter the soil.

If you can't find agricultural sweet lime at the garden center, try the farm supply places. The farmers definitely know the differencee.

    Bookmark   March 24, 2008 at 12:55AM
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"Due to various factors, among them lack of knowledge by OG Magazine founder JI Rodale, many organic gardeners only use dolomite, and many garden centers only sell dolomite."
I'm not sure where that came from but it is egregiously erroneous. Also most garden centers around here sell a calcitic lime even though the sandy soils here most commonly have low levels of magnesium.

    Bookmark   March 24, 2008 at 7:15AM
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Those links were interesting reads, thanks. I hadn't known much of that about Albrecht and since what little I pretend to know about soil chemistry
comes from Acres USA its good to have that balance.

However if these studies are to be born out what are we then to make of the fact that imbalances in Ca Mg lead to very undesirable soil structures?? Would you say this was an indicator rather than causal in nature and if so then aren't we saying on some level that we don't really understand what the hell pH is?? Its hard to imagine a soil with excessive levels of Mg not being underproductive.

If you've got links to other similar studies I'd enjoy reading them.

    Bookmark   March 24, 2008 at 4:45PM
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As far as the "fact" that imbalances in Ca to Mg lead to undesirable soil structures, I haven't read a study that makes or refutes that claim. (If I have time today, I may try to hunt something down). My only personal experience with magnesium dominated soils is the serpentine soil type in which Mg can be tens of times higher than calcium. In those cases, the soil has so many problems, including high salts and heavy metals, that it is hard to pin poor plant performance (with the exception of species endemic to those soils) on any one factor.
Soil structure is not one of those problem. In my experience, those soils drain very poorly due to high clay content rather than poor structure. At the same time I have heard from colleagues and read in literature about cases in which drainage in serpentine soils with very high Mg to Ca in other areas has excellent structure and drainage; so good in fact that water retention is another factor to add to the long list of problems for plants in those soils. In both cases, differences in drainage characteristics seem to be more a function of soil texture (a ratio of sand, silt and clay) than chemistry since the Mg to Ca ratios are similar in soils that physically behaves very differently. But again, serpentine soil is my only experience with magnesium dominated soil and does not represent a complete understanding of the topic.
I'm afraid I don't understand your concern about pH.

    Bookmark   March 25, 2008 at 8:41AM
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I suspect the key component we're leaving out is % of OM and I wonder if any of the studies from the links you posted controlled for that. I'll have to check back.

In my experience soils with high Mg are tight soils inclined to crust and very poor drainage. Yes they tend to be heavy clay soils but their performance is well below that of other heavy clays with a more balanced ratio. I don't have any experience with high Mg soils that perform or drain well but then again I think it may not be particularly useful to look at those ratios in isolation without factoring in OM.

The pH issue, for me at least, is understanding the triggering mechanisms.

    Bookmark   March 25, 2008 at 8:59AM
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In your Mg soils that crust and don't drain, you wouldn't happen to have any Ca, Mg, and Na data from a saturation extract would you? I'd like to take a look at those numbers if they were handy. And as long as I'm making a wish list, particle size data would be nice as well because that can change considerably from one observably heavy clay to the next observably heavy clay.
Is it a concern about what triggers pH changes, or are you wondering what is triggered by acid or alkaline soil reaction?

The O.M. is a good point and worth looking in to.

    Bookmark   March 25, 2008 at 9:28AM
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No I don't have any of those soil test results unfortunately. They're all the property of other people.

As far as the pH issue goes I have several friends in turf management who are verrry disdainful of pH as a sole indicator of anything and almost never treat it as an issue of of lime or gypsum but rather look to that underlying ratio. Same guys are doing more bio-assays than standard soil testing and applying one heckuva lot of compost tea. Its kinda out there I'll admit but they're getting some good results. In any even its made me start rethinking pH.

    Bookmark   March 25, 2008 at 10:18AM
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Belgianpup(Wa/Zone 7b)

I wouldn't get all whacked out of shape about changing soil pH. If you make a point of getting your basic soil nutrients in order, the pH will adjust itself.

Your test:
Calculated CEC 13
%K: 2
%Ca 26
%H: 65
%Mg: 7

The best calcium percentage in soil is between 60-70%. The best magnesium percentage is 10-20%. Heavy clay soils should probably be about 70/10, sandy soils closer to 60/20.

Your calcium is low, but if you look at your Cation Exchange Capacity (CEC) figures, your Magnesium is only 7%. That is hardly excessive. I would use dolomite lime, as you need an increase in both calcium and magnesium. These two work together. You need to get them in approximately the right percentages before you even try to fix anything else.

Take both your percentages and add them together, and they should total about 80%. Yours: 26%Ca + 7%Mg = 33%. That's not even close.

If your magnesium WAS high, you wouldn't be able to get rid of it until your calcium level is at least 60%. Once your soil hits 60%, the soil gets loose enough for magnesium and sodium to move out with rainfall or irrigation.

Your test recommendation suggests adding 220 lbs lime to every 1000 sqft of soil. That's equal to 9460 lbs of lime per acre, more than the 4-ton max advisable. And even at the maximum, it will still take three years for the lime to disintegrate and become part of the colloidal complex, at which time the plants will benefit, IF the lime was finely ground enough.

If you have your soil tested every year, you'll know where you are and where you should be going. Because of that 3-year lime thing, always tell the lab when and how much you applied. Otherwise, they'll keep telling you to add more lime, and more lime, and by the time all the lime is broken down, your soil will be lime-toxic. In fact, keep good track of whatever nutrients you add to the soil, and inform them when you send a soil sample in.


    Bookmark   March 25, 2008 at 8:20PM
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so far all i've done to the lawn was add alfalfa pellets, 50 lbs. over 3,000 sq. ft.
and 6 - 40 lb. bags of calcitic lime over the same 3K sq ft.
(that is my front yd.- 30 X 100 ft.)

so should i find a way to raise both mg and ca w/o using lime like someone suggest earlier? because ph would adjust?
or should i use sweet lime or dolomitic?

    Bookmark   March 25, 2008 at 9:59PM
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An article in SFGate with a title of "Are Tomatoes an Acid-Loving Plant?" said,
"If you've treated your tomatoes with calcitic lime to prevent blossom end rot, this may have raised pH levels to an undesirable level. Instead, use gypsum or calcium nitrate to increase the calcium content of the soil without raising pH."

Could you please comment on it?

Here is a link that might be useful: SFGate: Are Tomatoes an Acid-Loving Plant?

    Bookmark   August 4, 2013 at 12:14AM
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Tomatoes, like all other vegetables, prefer a soil that is slightly (6.0 to 6.8 pH) acidic. Back when the soil I have had a pH of 5.7 tomatoes, and most everything else, did not grow very well and I had problems with Blossom End Rot and many other things. After getting the soil corrected, copious additions of organic matter, so the soil pH was better (7.2) and nutrients were in balance the problems with BER and most other plant problems became a thing of the past.
California soils, because of the rainfall, tend to be alkaline, ie. too much Calcium in the soil. According to a friend that gardens in the San Diego area most of that Ca is not available to plants due to lack of adequate organic matter in the soil so California soils may need lime added so that Ca is available to plants, somewhat contradictory to what the soil scientists tell you.
vkelman, the article is somewhat accurate as far as it goes, but it does not tell the whole story.

    Bookmark   August 4, 2013 at 6:24AM
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I'd like to reopen this case about the Ca/Mg ratio and levels and my soil test results. I have some additional info....

I recently sat down and looked at the 4 soil tests taken from years 2007 to 2010. They come from three different testing companies, and the last test came from the area where I started a veg. garden (the first three were sampled from my front yard. ) But the results seem wildly variant, so I will post the ph and Calculated Cation Saturation from each test, so you all can compare and tell me what you think!

2007: pH-4.4 cec-5.1 %K-1.3 %Ca-10.7 %Mg-5.6 %H-83.1
2008: pH 4.8 cec 13 %K-2 %Ca-26 %Mg-7 %H-65
2009: pH 5.3 cec 9.1 %K-2 %Ca-53.5 %Mg-11 %H-33.4
2010*: pH 4.1 ---- K-36ppm Ca-479ppm Mg-31 ---------

* denotes a test of an area about 100 feet from the soil sampled for the other tests.
Let me also add the test agencies:
2007-A&L Analytical Laboratories, Inc.
2008- U of Kentucky agriculture
2009- A&L Analytical Laboratories, Inc.
2010- Texas A&M Extension

So as you can see, the ph numbers seem to be climbing in the direction I wanted them to. But the Cation numbers seem to be kind of random. After doing some research about all of this stuff, Im left wondering which soil test is going to be the most accurate??? It would be one thing if the Ca/Mg ratios were consistent but they anything but.


    Bookmark   August 9, 2013 at 1:48PM
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The CEC, or Cation Exchange Rate, is a calculation of how things in the soil should exchange, transfer. There are a number of things that affect that although generally adequate levels of organic matter seem to provide the best CECs.

    Bookmark   August 10, 2013 at 6:52AM
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I read a few short articles on this subject. Some just talk about pH and how to adjust it. They might mention it would be a good idea to get a soil test, but nothing more.

Other articles talk about pH but also potassium, calcium, magnesium, and sodium as well.
"Please Stop Liming you Soil Based on the pH!" is one of the former.

    Bookmark   August 10, 2013 at 4:14PM
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Yeah I think I've actually been reading that post haha. It has me I ready to learn but the only thing that's holding me back is these test results. They are seem like random number when you compare them. So how would I know which on to go by? What I was actually thinking was to take to diffent soil samples from the same plot, that way I could have the soil effectively 'tested twice'. Then, hopefully, the results will be consistent enough for me to have a more specific direction for which to take my soil-building regimen.

    Bookmark   August 11, 2013 at 1:34AM
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Btw, feel free to stop me from doing the tests if you think I've already got enough info the get started.

My nightshift sched makes dropping off soil test difficult and eventual, I'd just like to get started soonerâ¦

    Bookmark   August 11, 2013 at 1:37AM
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