What Is Dolomite Lime? (10 Common Dolomite Lime Questions)


Lawns and gardens tend to become more acidic over time, especially if you use nitrogen fertilizers.  You may have heard of lime for adjusting soil pH, but there is another option: dolomite lime.

So, what is dolomite lime?  Dolomite lime is a type of lime containing both calcium carbonate and magnesium carbonate.  It comes from underground limestone deposits, which appear as white, tan, gray, or pink crystals.  Dolomite lime is used to raise soil pH, and it adds both calcium and magnesium to soil.

Of course, it helps to get a soil test so that you can figure out exactly how much dolomite lime to use.  This will depend on your current soil pH, desired soil pH, and soil type (more detail on this later!)

In this article, we’ll talk about dolomite lime and what it does for soil.  We’ll also discuss when and how to use it.

Let’s get started.

What Is Dolomite Lime?

Dolomite lime is a type of lime that contains both calcium carbonate and magnesium carbonate.  According to Wikipedia, the amounts of calcium and magnesium in dolomitic limestone are about equal.

Dolomite lime comes from underground limestone deposits.   In nature, it can form white, tan, gray, or pink crystals.

dolomite limestone
Dolomite lime can appear in nature as white, tan, gray, or pink crystals.

Dolomitic limestone is often processed into dolomitic lime pellets or powder.  This makes it work faster when applied to garden soil.

What Does Dolomite Lime Do To Soil?

Dolomite lime has a few primary effects:

  • It adds calcium to soil
  • It adds magnesium to soil
  • It raises the pH of acidic soil (making it less acidic)

The 3rd effect (raising pH) is really caused by the first two.  With more calcium and magnesium ions in soil, the pH is increased (making soil less acidic).

ripe tomatoes on vine
Most plants like a soil pH of 6.0 to 6.5. Dolomitic lime can help maintain an ideal soil pH level.

As a secondary effect, dolomite lime can make nutrients available to plants.  Once the soil pH is adjusted to proper levels, nutrients become more available to plants.

You can see a graphic of nutrient availability by soil pH on this page from Research Gate.

According to the University of Florida Extension, raising pH will also reduce aluminum toxicity (which becomes a problem when pH is below 5.5).

Will Dolomite Lime Lower pH?

Dolomite lime does not lower pH.  Dolomite lime raises pH by adding calcium and magnesium to the soil.

If you want to lower soil pH, consider adding elemental sulfur.  Adding ammonia based fertilizers will also lower pH to make soil more acidic.

sulfur powder
Elemental sulfur will lower pH when added to soil.

You can learn more about ways to lower soil pH in my article here.

What Is Dolomite Lime Used For?

Dolomite lime is used for raising the pH of acidic soil.  It is often used as an alternative to lime when the soil also needs a magnesium boost.

The danger of using ordinary lime is that too much calcium in soil can prevent uptake of magnesium by plants. Using dolomite lime instead will add magnesium and calcium to soil in more equal amounts.

Dolomite lime can also be used as a supplement in magnesium deficient soil.  However, it will also add calcium.

If you want to add magnesium without calcium, consider using Epsom salt (but not too much!)

If you want to add calcium to soil without adding magnesium or raising pH, consider using gypsum (calcium sulfate).

magnesium sulfate epsom salt
Epsom salt (magnesium sulfate) adds magnesium and sulfur to soil without adding calcium.

When To Use Dolomite Lime

The University of Maryland suggests that fall is the best time to use dolomite lime.  However, it can be applied at any time.

The best indication of when to use dolomite lime is:

  • when the soil is acidic
  • when magnesium levels are low

In the first case, you can use either lime or dolomite lime.  In the second case, opt for dolomite lime, since it contains magnesium.

calcium carbonate
Ordinary lime (calcium carbonate) raises soil pH, but dolomite lime also adds magnesium.

In order to tell whether your soil has low pH or magnesium levels, a soil test is necessary.  You can learn more about soil testing in my article here.

How Do You Add Dolomite Lime To Soil?

The best way to add dolomite lime to soil is to till it into your garden.  According to the North Carolina State University, lime has the most benefit when mixed into the soil.

If you cannot rototill (or want to maintain a no-till garden), then you can still apply dolomite lime.  Simply use a fertilizer spreader to distribute the dolomite lime over the soil surface.

fertilizer spreader
Use a spreader to distribute dolomite lime over the soil in your garden.

This method will take slightly longer to affect pH, but it will still work.

Of course, another option is to mix a little dolomite lime powder or pellets into the soil where plants will grow.  This will not change the pH of the entire garden, but it will save on the cost of lime.

Note: if you need to add more than 50 pounds of lime per 1000 square feet, the University of Maryland suggests splitting dolomite lime into two applications: one now, and one in 6 months.

How Much Dolomite Lime To Use In Soil

A soil test is the best way to determine how much dolomite lime to use in soil.  According to the University of Alabama Extension, soil testing labs check soil pH and buffer pH to give you an accurate recommendation for the proper dolomitic lime application rate.

The amount of dolomite lime to use will depend on several factors, including:

  • Current soil pH (the pH of your soil right now)
  • Desired soil pH (the pH you want – this depends on the crop.  For example, blueberries need more acidic soil than tomatoes).
  • Soil type – the amount of lime depends on whether you have clay, silt, or sandy soil.
clay soil
Clay soil will need more lime than sandy soil.

Remember that pH works on an exponential scale, not a linear scale.  This means that a pH of 5.0 is 10 times as acidic as a pH of 6.0, and 100 times as acidic as a pH of 7.0.

As a result, you will need a lot more lime to raise pH from 5.0 to 6.5 than if you only need to raise pH from 6.0 to 6.5.

Be sure to read the package label before applying dolomite lime (or any other soil additive) to your garden. Remember: it is possible to add too much lime to your garden!

Down to Earth suggests using the following amounts of dolomite lime per 100 square feet:

  • 3 pounds if your current soil pH is 6.0
  • 5 pounds if your current soil pH is 5.5
  • 10 pounds if your current soil pH is 5.0

You can find dolomite lime from Down to Earth here.

How Long Does It Take For Dolomite Lime To Work?

According to the Michigan State University Extension, you may see the effects of dolomite lime (higher pH, magnesium, and calcium levels in soil) after a few months.

However, it can take 2 to 3 years for lime to completely react with soil, depending on soil acidity at the time of application.

The particle size of dolomite lime also affects how fast it works.  A smaller particle size (powder) works faster than a larger particle size (pellets).

dolomite limestone
Dolomite limestone ground into powder will work faster than pellets.
Image courtesy of user:
Amcyrus2012 via:
Wikimedia Commons: https://commons.wikimedia.org/wiki/File:
Dolomitic_Limestone_Label.JPG

Use dolomite lime powder if you want a faster pH change.  Use dolomite lime pellets if you want a slower pH change over a longer time period.

Can You Mix Dolomite Lime With Water?

You can add dolomite lime to water to raise the pH and to buffer the pH.  According to the University of Alabama Extension, dolomite lime helps to maintain pH between 7.0 and 8.5 (by acting as a buffer).

It also makes nutrients more available to organisms in the water, such as algae.  The best time to lime a pond is before you fill it.

pond water fountain
Dolomite lime can buffer the pH of water in a pond and make nutrients more available.

If the pond is already filled, then late fall or winter are the best times to add lime.

What Is The Difference Between Lime & Dolomite Lime?

Lime and dolomite lime both contain calcium carbonate, and they are both used to raise the pH of acidic soil (known as liming).

However, there are some differences between the two.  For example, dolomite lime contains magnesium (in the form of magnesium carbonate), while lime (calcite lime) does not.

The percentages by weight of various elements by weight also vary between these two types of lime:

  • Calcium carbonate contains 40% calcium, 0% magnesium, 12% carbon, and 48% oxygen by weight.
  • Magnesium carbonate contains 0% calcium, 28.8% magnesium, 14.2% carbon, and 57% oxygen by weight.

The following table summarizes the comparison between garden lime and dolomite lime:

AttributeCalcitic
Lime
Dolomite
Lime
Calcium34%23.5%
Magnesium0%9.5%
Calcium
Carbonate
86%49.8%
Magnesium
Carbonate
0%32.9%
CCE (calcium
carbonate
equivalent)
90%98.2%
This table summarizes the comparison
between lime and dolomite lime.

Is Dolomite Lime Good For Lawns?

Dolomite lime is good for lawns because it raises pH and adds both calcium and magnesium to soil.  Having the proper soil pH makes fertilizer more effective and makes nutrients available to plants.

According to Baker Lime, 20% of fertilizer is wasted at a soil pH of 6.0, while none is wasted at a soil pH of 7.0.

grass
Dolomite lime raises pH and provides calcium and magnesium to help grass grow better.

Over time, the soil in your lawn or garden can become more acidic due to:

  • Nitrogen fertilizers (many ammonium-based fertilizers increase soil acidity)
  • Plant growth (plants remove calcium and magnesium from soil as they grow)

Dolomite lime can also be good for citrus trees, tomatoes, potatoes, roses, and other crops that need a boost of magnesium or an upward adjustment to their soil pH.

Conclusion

Now you know all about dolomite lime: what it is, how it is used, and when to use it.  Remember to get a soil test to help you find out exactly how much of a soil amendment to use.

I hope you found this article helpful.  If so, please share it with someone who can use the information.

If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here.  Enjoy!

~Jonathon

jonathon.david.madore

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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