# Fast vs slow lime



## Virginiagal

There was discussion about the relative merits of fast acting lime and regular lime on this thread
https://thelawnforum.com/viewtopic.php?t=23397
and I think we should get out of the poster's thread and continue over here, if you all want to continue the discussion.

@OnTheLawn argued the benefits of regular lime. I'll copy part of his argument (other part was lower cost):
"So here's another way to think of it: frequency curve.

The goal is to basically get the line to rise from 5.3 to the optimal range. The two options for doing so are using fast-acting lime, or regular lime. The fast-acting lime will move the line quicker to optimal, but it will also eventually go back down because it's using calcium carbonate EQUIVALENTS. They break down faster, but also don't have as much of a long term effect. So, the frequency curve will have peaks and valleys on your way to optimal range and it will take longer to get there. Again, you'll have a more immediate impact though.

The regular lime will be more of a straight line to optimal range, so it won't have those peaks at optimal range that the fast-acting lime has, but it also won't have the immediate impact."

@ken-n-nancy argued the benefits of fast acting lime. Here is his post:
"I've been trying to avoid turning this thread into a fast-acting lime vs. slow-acting lime pro/con, but since we kind of ended up going there, there are a couple things I wanted to mention while we were on the topic...

First off, I think that @OnTheLawn is right that traditional lime (which I suppose one could call slow-acting) will end up being less expensive, in the long run, than using the fast-acting limes which have additives which help solubilize the calcium like SoluCal (Lowes Sta-Green).

Before talking about some other advantages of fast-acting limes which help solubilize the calcium, a bit of background is in order. There are two different primary approaches to make "fast acting lime" in products on the market:
The first of the approaches for "fast acting lime" is to grind the limestone particles as finely as possible, to increase their surface area so the calcium becomes available in the soil solution more quickly. This is traditional "fast-acting lime." The lime can either consist of very fine particles (practically a dust, as in the lime that one uses to mark lines on a sports field) or the very fine particles can be re-pelletized using a dissolvable binder which allows the pellets to be spread in a broadcast spreader. (Lime that is pulverized into dust won't spread properly in a broadcast spreader, although a drop spreader will do fine.)
The second approach for "fast acting lime" is to use additives which act as chelating agents to keep the desired nutrients (calcium, in this case) from getting bound up in the soil and instead be available for plant uptake. This is a distinct approach from the "fine particles" approach described above. Adding to the confusion, though, as far as I know all "fast-acting lime" products which make use of chelating agents (e.g. SoluCal, Mag-I-Cal, or Encap (now "Earth Science")/Pennington) also make use of pelletization of finely-ground particles, too.
So, on to some of the advantages of the fast-acting limes which haven't yet been mentioned in this thread...

One of the advantages of the limes which use the chelating approach is that the response is seen more quickly -- on the order of months rather than years. This means that if one's soil is deficient in calcium, a fast-acting lime will make the calcium available to the plant at the appropriate level in months, rather than years. If somebody has done a soil test and wants to correct a low pH problem, the fast-acting limes fix the problem sooner.

Another advantage is that the fast-acting limes reduce the risk of long-term overshoot. Soil tests have a significant amount of variation from test to test. Much of this variation for things like calcium have to do with which particles from the soil end up in the sample which is actually tested. Soil isn't homogeneous like chocolate pudding, but is made up of an aggregate of all kinds of particles. Depending upon which particles end up in the test tube, the test results can have significant variation. If the sample happens to have a random abundance of limestone in it (maybe some small chunks), the test results will be higher than normal. If the sample happens to have dodged limestone chunks that are present in the soil in the lawn, but just not in the sample, then the test value will be lower than normal.

Since there is a fair bit of normal variation in the test values, let's consider the case where a soil test is a natural "outlier" indicating low calcium, which is then remedied by making a single large application of traditional lime to make up for the entire shortfall. The immediate effect upon the plants is not a problem due to the slow-acting nature of the traditional lime but the overshoot will happen and there isn't much one can do about it once the large application as been made. Even if one is to retest the next year and identify that overshoot has taken place, the slow-acting nature of the traditional lime means that the overshoot is going to persist for a couple years until natural leaching of the calcium from the soil takes place. (I'm assuming one is in such an environment, or one wouldn't have needed to apply lime in the first place.) If, however, that shortfall from the "outlier" indicating low calcium is remedied by application of fast-acting lime, then there will be a near-term overshoot (due to applying the amount of lime recommended by the "low outlier" test), but by the time of a retest the next year, there is no longer a significant remaining "pending overshoot" that will persist for years.

In any case, I believe the above two items (quicker response and less risk of long-term overshoot from an outlier test) are advantages of the fast-acting lime that may make the added cost worth it. Then again, maybe I've just bought into some of the marketing hype of companies like Solu-Cal and Encap in promoting their products."

********

My position is both limes are fine. Fast acting limes are good when a quick pH change is needed. Regular lime is good in general to correct pH. The main problems with fast acting lime are they are more expensive, you have to make more applications, and when you need a lot of lime, a bit here and a bit there doesn't do the job. I dislike the marketing of fast acting lime which makes the customer think one bag of fast acting lime will take the place of 3 or more bags of regular lime. It's not true, If the lab has determined that you need 100 lb/1000 sq ft to raise your pH to the target, you need 100 lb/1000 sq ft, whether it's fast acting lime or regular lime. You need the carbonic action from a certain amount of product.

Ken-n-Nancy says regular lime won't raise pH for years. It is slower acting than the fast acting lime, but regular lime has enough fine particles to be reacting in months. I like the fact that regular lime will continue to work for up to three years. You get a continuous protection from acidity and don't have to do a soil test but every three years or so.

Ken-n-Nancy is concerned that a large application of regular lime will overcorrect pH. The labs do a buffer test measuring resistance to pH change and their target likely is 6.5, so their recommendations are tailored for the particular soil being tested and the target leaves room on either side. Grass in general is happy between 5.5-7.0. I have not heard stories of "I applied what the lab said and now my pH is way above 7.0."

A few years ago I was in training to be a soil advisor in another forum. They used a lab that did not make recommendations, did not do buffer tests. So the tests gave no guidance on how much lime was needed. The forum advisors simply recommended fast acting lime to everyone who needed lime, the rationale being that the small amounts this year would raise the pH for now and there would be another soil test next year. But some people really needed a lot more lime than the 10-30/1000 sq ft that fast acting lime would allow in a year. I disagreed with that approach. It's much better to know that you need, say, 150 lb/1000 sq ft, and you can then make plans for how you want to address it.


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## g-man

@Virginiagal great idea to split this.


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## Virginiagal

For anyone new tuning in, fast acting lime is calcitic lime advertised to work faster. It is generally limited to around 10 lb/1000 sq ft per application (it varies somewhat among brands). Regular lime is lime that is expected to work over around three years. It is limited to 50 lb/1000 sq ft for applications not tilled in. I have never seen fast acting dolomitic lime. Regular lime can be dolomitic or calcitic. I am delighted that regular calcitic lime is now being carried by big box stores. A few years ago when. I last went shopping for lime, all they had for calcitic lime was the fast acting kind.


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## Ridgerunner

> slow acting lime is calcitic lime advertised to work faster


Hence, the label "slow."


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## g-man

I will share my thoughts in the subject. My thoughts are for topdressing of lime and not for tilting in. For tilting I would try to use a fast lime.

Each bag of lime of fast acting lime is sold with a table describing the content. In there you will see an equivalent liming. It seems that each state asks for a slightly different calculation. But most end in the ~90%. To me that means that they are slightly less and not 3 times more effective than regular lime.

When a lab does their analysis and recommendation of how much lime to do, it is a scientific approach to neutralize the extra hydrogen in the soil. pH is the measurement of hydrogen in a log scale (not linear). Typically they recommend the lime to address the top 6 inches of soil. If they say you need 100lb/ksqft, it is because that's how much hydrogen needs to be addressed in the 6 inches of soil.

In my opinion, when you then apply 10lb/ksqft of "fast acting" lime, yes the smaller lime particles will be able to neutralize the top layer faster, but it is only 10lb. Great, the top 0.5-1in of soil might increase the pH from 5.5 to 6.0, but the other 5 inches of soil/roots are still not addressed. In a couple of months you then need to remember to do another 10lb, meanwhile the I *think* some of that top layer application moved deeper into the soil and the overall pH has to increase. This will depend on the soil structure. You will need to repeat this 10 times to get to 100lb, so around ~2.5 to 3 years.

Using regular cheaper lime, you can apply safely 50lb/ksqft. I've read that you can go even higher rates (100lb/ksqft), but I don't want to cause harm to a lawn, so I recommend the general 50lb/ksqft rate too. This lime has larger percentage of large particle size, so it takes longer to breakdown and react with the soil. The standard recommendation is that it takes 6 months to apply the rest of the lime. To me that's a big benefit of the regular cheaper lime. You can apply it Oct/Nov and let it do it's thing thru the winter. Freeze / thaw cycles / rains will help it move deeper into the soil until May. In May you do your next application and continue to correct the pH, but now you likely have your 6in of soil at least 50% better. In the 100lb example, you are done with lime in two 50lb applications.

Lastly, lets not forget the goal with pH correction is to get us closer to the ideal range for better nutrient availability and growth. Unless you are in the 4.0 pH range, you are not going to see a huge improvement from 5.5 to 6.0.


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## ken-n-nancy

Thanks, @Virginiagal, for moving the conversation about lime to a different thread. You did a good job of including earlier points in their context.

I don't have a strong opinion about the use of traditional limes vs. fast-acting limes. I think there are some advantages to either approach, and, as with many lawn care challenges, there are multiple ways to get to a good lawn.

The reason for my earlier posts describing some advantages of fast-acting limes was because the earlier dialogue mentioned only the advantages of traditional liming approaches, and I wanted to mention some of the advantages of the approach that uses fact-acting limes and annual soil tests, in order to help inform the decision-making process for homeowners to decide how to care for their lawns after receiving their soil test results. I wasn't insisting that one approach was inherently better than the other -- I think both have their relative use cases, depending upon the objectives, maintenance level, and budget of the homeowner.

Thanks again!


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## Ridgerunner

:shocked:


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## Virginiagal

So there is a fast acting dolomitic lime. What do you think of the effective neutralizing value? Seems rather low.


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## Ridgerunner

Virginiagal said:


> So there is a fast acting dolomitic lime. What do you think of the effective neutralizing value? Seems rather low.


What? The product I posted above?
No.
Yes the ENV. So, it wouldn't be considered fast acting by any means.
(Forgot you started a new thread)
Reference this:


> One way to compare lime products is to use the ENV number on the labels. ENV is a calculation for the 1 year effectiveness of a lime product based on it's "fineness" (grind/mesh) and its CCE (quality/content of carbonate).
> See ENV on the labels:
> Solu-Cal
> https://www.solu-cal.com/media/pdf/prod ... 019WEB.pdf
> Espoma
> https://www.domyown.com/msds/ESPOMALIGH ... TSHEET.pdf
> with the SoilDoctor label above.


Soil Doctor
https://i.postimg.cc/2SCHvJ2H/E6-FEF64-B-E93-F-4514-A614-3949-EA900-B1-A.jpg


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## Virginiagal

@Ridgerunner It says "quickly regulates the pH..." What point are you making by posting the image?

@ken-n-nancy Annual tests can be useful for P And K and comparing to previous tests. But for liming purposes, I think it's best to go by one test, doing what the lab recommends, and then wait for those applications to play out. VA Tech asks on its soil test form if you've applied lime within the last year and it assigns a lime credit if you have. What is very important is to have a buffer test done, which is normal for most labs. Some soils are very easy to adjust, others take lots and lots of lime. You don't know what kind you have and how much lime you really need without a buffer test.


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## OnTheLawn

Fast acting dolimitic lime (can be found at Home Depot):


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## OnTheLawn

I applied the above lime in preparation for my renovation. My pH was a 5.4, so while not ideal, it was fine for TTTF and I decided to put out the 8 lbs/m (or 7, I can't quite recall but it's in my journal). I was also low in Mg, so put this down to help correct it. I'm sure I could apply again, but I'm going to wait until early spring before my first fertilizer app to soil test again and see where I'm at. Will be reporting back!


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## Ridgerunner

@Virginiagal Just my twisted sense of humor, I guess.

This conversation is getting to be pretty convoluted, as will happen when attempting to explain a complicated process.

@ken-n-nancy , @Virginiagal and @g-man have presented valid and important factors to be considered for pH remediation through lime applications.

I'm not the right Huckleberry to clear it all up, nor am I inclined to put in the necessary effort.

However, to help prod the effort along, and a little house cleaning, I defer to and offer:

This is the most comprehensive/informative and easiest to understand explanation of liming I have encountered. If's been my go to for general overview information and as a refresher:
http://pubs.cahnrs.wsu.edu/publications/wp-content/uploads/sites/2/publications/fs213e.pdf

Term clarification:

The commonly accepted definition of "agricultural limestone aka Aglime," means any limestone product whose calcium and magnesium compounds are used for the purpose of neutralizing the acidity of soil.

However the individual States have their own definitions for Aglime set by law.
So what an individual author might mean when using the term can get pretty confusing. For instance:
Kentucky KRS 250.670 considers ground limestone to be agricultural limestone only if it meets the following three minimum standards of quality: 
1. 80% calcium carbonate equivalence (CaCO3)
2. 90% of the product passes a 10-mesh wire-screen sieve 
3. 35% passes a 50-mesh wire-screen sieve 
When talking to a soil scientist from Kentucky is he using the generic definition or his State's codified definition? When some University labs make their recommendations to apply X pound of Aglime, it's based on their home State's codified definition of Aglime.

Soil Test Lab Recommendations

The type of lime upon which these recommendations are based can vary from a 70 to a 100 CCE quality lime. Also the soil depth of the recommendation can vary from 6 to 9". You'll need to do your research and a little math to determine the amount of YOUR purchased lime needed to change the pH of your soil to a desired depth. In addition, although many Labs target 6.5, it's not unusual for a lab to target 6.4 or 6.8.
I believe lime recommendations from Midwest are for a 9" depth using an "Ag-ground lime of 90%+ TNP or CaCO3 equivalent, and fineness of 40%100 mesh, 50% 60 mesh, 70% 20 mesh, and 95% 8 mesh."

Studies have shown that surface liming affects the top inch or two of soil within months but the next inch can take as long as 4-5 years with no significant increase in pH occuring below 3" after a period of 5 years. In addition pH results are and remain stratified.
https://www.agronomy.k-state.edu/documents/eupdates/eupdate012513.pdf
https://www.ag.ndsu.edu/cpr/soils/growing-problem-of-surface-soil-acidity-in-long-term-no-till-05-24-18
and (see topic "Placement")
https://www.cropnutrition.com/nutrient-management/soil-ph
and pH at different depths of surface applied lime after 24 years
http://corn.agronomy.wisc.edu/Management/pdfs/a3671.pdf
I'll hold off on the sites explaining the chemical reaction that change pH using carbonates.
Remember all the while we are raising pH, the soil is being acidified by rain, roots, OM decay, subsoil pH reserves and fertilizers.

The question that I have is how much of a pH change and how quickly can a change happen in the top layer of soil without damage to the turf or soil?


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## ken-n-nancy

Ridgerunner said:


> ... Studies have shown that surface liming affects the top inch or two of soil within months but the next inch can take a period of 4-5 years. In addition pH results are and remain stratified.
> https://www.agronomy.k-state.edu/documents/eupdates/eupdate012513.pdf
> 
> ...
> 
> The question that I have is how much of a pH change and how quickly can a change happen in the top layer of soil without damage to the turf or soil?


Thanks, @Ridgerunner for sharing the various articles you mention. I find the above article you referenced from Kansas State to be particularly interesting, as it discusses studies for no-till farming (which is more similar to our "no-till" home lawns than traditional tilled fields) which focus upon surface application. Definitely some relevant items to consider in there. It also has me wondering if the acidification due to surface-applied nitrogen fertilizers (which many/most of us do) has a similar effect of having the pH change be mostly in the top layer of soil. In that case, reversal of that effect (through application of lime) also makes sense to be surface-applied, too.

In any case, thanks for sharing! It's fun to learn new things applicable to our lawn care!


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## Virginiagal

Thanks for the info on fast acting dolomitic lime, Onthelawn, and all the links, Ridgerunner. That's a good question about surface application and turf damage. Years ago before I knew anything and I first started applying lime, I asked several sources about applying lime at seeding and was told "no problem." So I did. But since then, I would not do that. It raises the pH right at the surface just when seedlings would be germinating. How much? I don't know. Much better to apply in late fall when winter freezes and thaws will let the lime get into the soil. Your articles indicate that lime doesn't do much for soil below 3 inches. Maybe we should all be doing more to promote earthworms. We need better soil mixing. Earthworms would help with aerification too.


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## Ridgerunner

Thanks @ken-n-nancy and @Virginiagal I realize that those citations don't resolve all the issues involved, but hopefully they help to at least identify and explain some of the many factors to be considered.


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## ken-n-nancy

Virginiagal said:


> Maybe we should all be doing more to promote earthworms. We need better soil mixing. Earthworms would help with aerification too.


+1. I think earthworms are one of the best things for a lawn -- they provide natural aeration, break down thatch, convert mulched leaves and grass clippings into free fertilizer (worm castings) and basically just help make the soil a happy place for grass. Helping get that lime down into the soil would be a perk, too!


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## Ridgerunner

@ken-n-nancy As a follow up to your earlier post regarding the advantages to fast acting limes:
I can't say this list of additives is conclusive, but based on packaging labels (AST-Advanced Soil Technology) and the Encap (inventor of "fast acting lime") lawsuit https://www.scribd.com/document/63195040/Encap-v-Oldcastle-Retail-et-al (thanks to thegrassfactor for providing me the link a couple of years ago) that identified the underlying patents, the major additive components:
1. Polyacrylamide (PAM) (Soil Moist and disposable diapers)
Significant Claims/characteristics:
*Binds soil to reduce erosion
*Binds nutrients reducing nutrient run-off and leaching--unknown whether this is chelation or another process.
*Water/moisture retention.
2. Lignosulfonates 
Significant Claims/characteristics:
*Dispersent
" Aids in the suspension of otherwise insoluble or poorly soluble substances in water. (CaCO3?)
3. Humic Substances (HA and FA)
Significant Claims/characteristics:
*Chelation, binds nutrients
*Water/moisture retention
*Agglomeration

Ken (or is it Nancy?),
I've never seen any studies that show any improvement in pH reduction due to the presence of these additives. I suspect under real world circumstances where soil moisture isn't monitored, there would be some increase in lime effectiveness, but where moisture is maintained and lime quality and grind is equal, I highly doubt the water holding characteristics of the additives would show any improvement. 
As to the chelation characteristics, other than a possible slight increase in CEC and the attendant reduction in nutrient run-off or leaching, I can't see any logical reason for an improvement in pH change. In fact, it might have a deleterious effect as the newly introduced cation sites compete with the current soil CE sites for Ca and Mg needed to displace H+ for the CO3 neutralization process.
Regarding the dispersing/"solublizing" characteristics, although intriguing, I wonder if it would have much impact on a process (pH reduction by CO3/H+ reactions) that takes months at best.
A study of equal liming materials with and w/o the additives would be welcomed.


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## Ridgerunner

ken-n-nancy said:


> Virginiagal said:
> 
> 
> 
> Maybe we should all be doing more to promote earthworms. We need better soil mixing. Earthworms would help with aerification too.
> 
> 
> 
> +1. I think earthworms are one of the best things for a lawn -- they provide natural aeration, break down thatch, convert mulched leaves and grass clippings into free fertilizer (worm castings) and basically just help make the soil a happy place for grass. Helping get that lime down into the soil would be a perk, too!
Click to expand...

Or core aeration prior to liming? just to add another controversial subject to the mix.


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## Virginiagal

Yes, core aeration would be helpful to get the lime into the soil. If people are doing it anyway and need lime, I encourage liming when the holes are open. That conflicts with "avoid at seeding" if they're seeding too. But too good a opportunity to get the lime further into the soil.

I'm pondering Ken-n-Nancy's question on acidification in the top layer of soil because of fertilizer: just where does this acidification take place? I've assumed it's at the root level and the roots are involved.


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## Ridgerunner

> just where does this acidification take place? I've assumed it's at the root level and the roots are involved.


It will occur wherever the microbes are-i.e at the vary surface and on down. Most acid production occurs during the processing of ammonium to nitrate-nitrification. I don't have a cite off hand, but as I recall most of this happens in the top inch.
When I was going through my bookmark library to find the cites I posted above, I came across one that gave the amount of lime needed to counteract the acidy of different fertilizers on a pound for pound basis. Sorry, not going to go back though 50+ bookmarks again, but i found this via google. This a chart, but it's pounds per acre, so some math will be involved.
Forgot the link:
https://ohioline.osu.edu/factsheet/AGF-505-07


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## zeroibis

OnTheLawn said:


> Fast acting dolimitic lime (can be found at Home Depot):


Strange the only dolimitic lime I have ever seen at HD was from Pennington (also fact acting) by me this is the expensive lime as your paying for fast acting.

The low cost lime that is like $4/40lbs is calcitic lime.

Now my understanding is that over the long run what I want is dolomitic lime to build up in the soil as it will stay there longer than calcitic lime. Issue for me is where to go to get this stuff for less in the future? Maybe SiteOne?


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## Virginiagal

@zeroibis If your soil is high in magnesium, use calcitic lime to avoid adding more magnesium. If your soil is low in magnesium, use dolomitic because you need more magnesium. If your soil is neither high or low in magnesium, you can use either. Pelletized is much better than pulverized, which is a mess to spread. You should not be adding lime without a soil test telling you how much you need.


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## zeroibis

@Virginiagal Yea I am actually adding both, soil is currently at 5.6 and I am low in everything except sulfur, sodium and boron.

My understanding was that dolimitic lime in general stays in the soil longer compared to calcitic lime and so to actually fix the problem over time it is dolimitic lime that I need to mostly add.

Or is it simply that you need to be using non fast acting lime if you want to have the ph change stick around for the long run.

I have no problem doing a mix of fast and slow dolimitic and calcitic to get a decent PH change now and down the road.

Currently I have applied 10lbs/1000sqft of calcitic lime. I plan to add 10lbs/1000 of dolimitic lime (AST) in a few weeks. I then plan to repeat this in the spring. I will then run another soil test before applying any other limes to see where I am at.


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## Virginiagal

@zeroibis The lime that is not fast acting will react over a period of years, some of it quickly, some in a few months, some later, some much later. So it sticks around and you can apply up to 50 lb per 1000 sq for at a time (usually fall and spring). What did the lab recommend? For the fast acting, follow the bag directions. I would be wary of doubling up on fast acting applications. You don't have to get another soil test in the spring if the lab told you how many lbs to use. You can do what they say and retest in another three years or so. If the lab says you need 100 lb per 1000 sq ft, you need 100 lb of lime per 1000 sq ft, whether it is fast acting or not fast acting.


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## zeroibis

Virginiagal said:


> @zeroibis The lime that is not fast acting will react over a period of years, some of it quickly, some in a few months, some later, some much later. So it sticks around and you can apply up to 50 lb per 1000 sq for at a time (usually fall and spring). What did the lab recommend? For the fast acting, follow the bag directions. I would be wary of doubling up on fast acting applications. You don't have to get another soil test in the spring if the lab told you how many lbs to use. You can do what they say and retest in another three years or so. If the lab says you need 100 lb per 1000 sq ft, you need 100 lb of lime per 1000 sq ft, whether it is fast acting or not fast acting.


Oh I am not going to double up on the fast, I am putting slow out then fast a few weeks later and then repeating in the spring.

This will give me a total of 40lbs per 1000sqft which should raise PH by ~0.5 bringing me to 6.1 it. The amount of lime is just a construct of how high or low I want the ph to land in the target 6-7.2 range. So in my case I am just trying to at least cross the 6 and from there I got a lot of room if I over shoot at all and end up at 6.3 or something. I can always add more lime but I can not easily remove it if I go crazy so I am taking a measured approach as there is no sense in just buying a ton of lime trying to fix the problem all in 1 year when it is going to take a few years for the stuff to really fix the problem for good.

I am glad I asked about how long it lasts in the soil as it appears if I want to fix the problem in the long run I just need to focus on avoiding fast acting lime with things like AST and then just get calcitic or dolimitic based on calcium vs magnesium requirements.


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## g-man

How much lime did your soil report recommend?


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## Virginiagal

Some soils are highly buffered and it takes a lot of lime to change the pH. Some soils are lightly buffered and a small amount of lime will effect a change. The lab did a buffer test (I hope you used a lab that did one) and the amount of lime recommended is what it will take to bring YOUR soil up to the target pH (likely 6.5 but check with the lab o verify). So, what did the lab recommend?

Dolomitic lime contains both calcium and magnesium.


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## zeroibis

g-man said:


> How much lime did your soil report recommend?


Does not give me an exact amount. Just tells me PH is 5.6. I have clay soil so it should take ~40lbs total to go a .5 PH change.

Now obviously the bag rate for a 0.5 change is going to not exactly be 40 but when you look at the bags it basically adds to that across the two products and I am fine with aiming a little under.



Anyone have comments on this old video from grass factor on lime?


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## g-man

Mysoil values normally don't reflect the real soil pH. I would not use this to try to correct it. A good lab will tell you exactly how much lime to use.


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## Virginiagal

Since you're low in calcium and magnesium, dolomitic will supply both and would be a good choice.

You don't have any idea how much lime you need. You should get a soil test from a lab that does a buffer test.

I didn't watch the whole video (was not impressed). The fast acting lime will raise the pH faster but won't keep it up long term. It only supplies so much carbonic action for the amount applied. You need to use however much lime the lab recommends (and use a lab that makes a real lime recommendation).


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## zeroibis

Virginiagal said:


> Since you're low in calcium and magnesium, dolomitic will supply both and would be a good choice.
> 
> You don't have any idea how much lime you need. You should get a soil test from a lab that does a buffer test.
> 
> I didn't watch the whole video (was not impressed). The fast acting lime will raise the pH faster but won't keep it up long term. It only supplies so much carbonic action for the amount applied. You need to use however much lime the lab recommends (and use a lab that makes a real lime recommendation).


Yea that video is a few years old and appears to have vanished now... maybe he is going to make an updated one?


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## Virginiagal

His math was off too. Two tons is 4000 lb. There are 43.56 x 1000 sq ft in an acre. 4000 lb divded by 43.56 is 91.8 lb per 1000 sq ft. The part about ratios in the lime was weird. There is an approach to soil testing that targets certain ratios in the soil but I've never heard of targeting ratios in a product. The video was just generally misinformed. The first thing one should do is get a soil test (not just a pH reading) and I don't think I heard the words "soil test."

At this point you've just applied some lime and it could skew a soil test now if you get lime particles mixed into your sample. I suggest getting a soil test in the spring with a lab that will give you a lime recommendation and going forward with that. The soil test will be more accurate than the MySoil one and will give you your CEC number, which is good to know. And it will tell you just how much lime you need.


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## ken-n-nancy

zeroibis said:


> So in my case I am just trying to at least cross the 6 and from there I got a lot of room if I over shoot at all and end up at 6.3 or something. *I can always add more lime but I can not easily remove it* if I go crazy so I am taking a measured approach as there is no sense in just buying a ton of lime trying to fix the problem all in 1 year when it is going to take a few years for the stuff to really fix the problem for good.


Personally, I think the above approach, of making a small to moderate correction based upon a single soil test, aiming for the conservative side of the target pH of 6.5 - 7.0, and then retesting in a year, is a prudent strategy.

My reason for the above perspective is that I have seen that there can be significant variation in pH test results based upon a number of factors (the lawn soil being non-homogeneous, sampling location variation, sampling timing variation, sampling depth variation, effects of previously applied products, and test results variation, etc..) This means that when a test shows a particular result (say 5.6 as in @zeroibis' soil test), it is possible (even likely) that a new sample taken for a retest will give a different result. This is true even in circumstances where a "buffer pH" is measured and reported.

I have seen this variation myself, where in one test my pH was measured at 7.3 and a second test conducted 3.3 months later measured pH as 6.6, with hard-to-explain changes in the cations which are responsible for the pH changes. No lime applications were made between the two tests. Clearly, the "real pH" is probably neither 7.3 or 6.6, but probably somewhere in between (or maybe even outside that range a little.) In my case, I think most of the difference is based upon test result variation, rather than actual soil changes which dropped the pH from 7.3 to 6.6 in just over three months. In other words, at least one, if not both, of those tests must have been "an outlier" to some extent. If I had based a "full correction" lime application upon the lower pH test, I could potentially be in an overshoot situation that can only be fixed by waiting for the pH to drop naturally.

It is in avoiding a hard-to-correct overshoot condition, as well as providing a more neutral pH for the soil in the short term, that I think there is some merit to the "fast lime" side of the discussion. Yes, I realize fast lime is more expensive. As such, the amount of lawn to be treated is also a factor to consider -- for a small lawn of just a few thousand square feet, the cost difference in terms of dollars between "slow lime" and "fast lime" isn't huge. For a lawn of more than an acre, the cost difference is quite significant.

That said, particularly in soils that need a large upward correction in pH (say < pH 5.5), I think a hybrid approach (as @zeroibis suggests) of making an application of both (1) traditional (slow) lime to reduce the cost of the total correction over time, and (2) fast-acting lime to provide a near-term correction in pH for the existing lawn may be a balanced approach to reduce long-term cost, aid the lawn in the near-term, and reduce the risk of a hard-to-correct overshoot condition.

For those needing only a comparatively small pH correction (say 6.0 < pH < 6.3) on smaller lawns, I also think applications of fast-acting lime, with a subsequent retest the next year, make a lot of sense, in order to more quickly get to the target yet avoid overshoot due to variation in test results.



zeroibis said:


> I am glad I asked about how long it lasts in the soil as it appears if I want to fix the problem in the long run I just need to focus on avoiding fast acting lime with things like AST and then just get calcitic or dolimitic based on calcium vs magnesium requirements.


You definitely should choose between calcitic and dolomitic lime based upon calcium vs. magnesium requirements.

As to whether or not it is ever worthwhile to use fast-acting lime is a topic which does not have consensus amongst the current commenters in this thread.



Virginiagal said:


> At this point you've just applied some lime and it could skew a soil test now if you get lime particles mixed into your sample. I suggest getting a soil test in the spring with a lab that will give you a lime recommendation and going forward with that. The soil test will be more accurate than the MySoil one and will give you your CEC number, which is good to know. And it will tell you just how much lime you need.


I really like the above advice from @Virginiagal. Make a correction now (as you have done) and plan to get a better soil test next year.


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## Virginiagal

I think all of us here agree that fast acting lime is useful in certain circumstances. It is a good product. I have used it myself. My main concern is that it takes a long time doing applications twice a year over multiple years to get to the total needed if a lot of lime is required. So using ONLY fast acting lime can be a lot more work and more expensive. The first thing is to get a soil test that lets you know that total.

The manufacturers of the fast lime limit the amount used per application. You used a fast acting calcitic this month, correct? You could call and ask them if it's ok to do a modest (10 lb of slow acting lime per 1000 sq ft) application next month. It's so little, they may say it's ok. Or they may say you've done the limit on lime for the fall and wait for the spring. In any case, a pH of 5.6 isn't harming your grass (no toxicity issues). It just could be better. Waiting until spring for more lime is fine.


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## Ridgerunner

Before you apply any lime get a BpH test.


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