When looking into liming your lawn and garden for better grass and plant growth, you may run across mentions of two types of lime—calcitic lime and dolomitic lime—and wonder, “which type of lime should I use?”
Both calcite lime and dolomite lime will reduce soil acidity, which creates a more friendly growing environment in previously acidic soil, so both are effective. Calcite lime is typically the best choice for home applications because it provides faster results and is less likely to cause harm to the soil. Dolomite lime reduces soil acidity at a slower rate than calcite lime (a few months vs. a few weeks) and may have the side effect of hardening clay soils, which further inhibits plant growth. You should only apply dolomite lime if your soil is magnesium-deficient, which is defined as a 6:1 ratio of calcium to magnesium, based on a soil test.
Always perform a soil test, or have your soil tested professionally, before liming. Liming when your soil doesn’t need it can be harmful to plant growth. A full soil test will also help you determine how much lime your soil needs.
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Calcitic Lime vs. Dolomitic Lime
Both calcitic lime and dolomitic lime are made primarily from pulverized limestone. The difference in the types of lime are determined by the chemical makeup and mineral deposits in the stone itself. Studies from the University of Wisconsin show that overall, there is little difference in the long-term effectiveness of both varieties of lime.
Calcite lime is the most common type of lime available in most regions. It is a great choice for lowering the acidity of soil. Below are the key things to remember about calcite lime.
- Derived from limestone with calcium carbonate deposits
- Contains high calcium levels
- Contains little to no magnesium
- Fast-acting agent to reduce soil acidity (results with 2–3 weeks)
- Low risk of long-term soil damage
Calcitic Lime Uses
Calcite lime is usually the number one choice to reduce the acidity of the soil for home purposes. While both calcite and dolomite lime are fully absorbed into the soil over a 2–3 year period, calcite lime has much faster initial absorption. This means your lawn and plants will flourish faster following an application of calcite lime than with dolomite lime.
Calcite lime contains little to magnesium. This is only a problem in soil that is already magnesium deficient. Calcite lime will not solve, and will actually aggravate, an existing magnesium deficiency.
Typically, all soil becomes more acidic over time. This is accelerated in regions with sandy soil, where valuable nutrients are washed away by rain and watering. This leads to a rise in soil acidity. By applying calcite lime, you reduce soil acidity and reintroduce nutrients to the soil, creating a healthy growing environment for plants and grasses, as well as encouraging healthy microorganism growth. All this leads to better growth in previously acidic soils.
Is Calcitic Lime the Same as Agriculture Lime?
Agricultural lime is a catch-all term for lime formulations for agricultural use. Agricultural lime, or AgLime, can be found in dolomitic or calcitic varieties.
There are several different ways lime can be prepared for spreading and soil combination. You may see pulverized, pelletized, and hydrated lime. For lawn and garden use, pelletized lime is the best choice. It’s much more easily spread than pulverized lime, which can clog spreaders or blow away if not tilled into the soil. Pelletized lime, on the other hand, works well when spread over a recently aerated lawn or when added to garden soil.
Dolomite lime is typically less common than calcite lime and is more often reserved for special purposes. Below are the key things to keep in mind when considering dolomite lime.
- Derived from limestone with both calcium carbonate and magnesium carbonate deposits
- Contains lower levels of calcium
- Contains magnesium
- Slow-acting agent to reduce soil acidity (results in 2–3 months)
- Can cause soil compaction in hardening in clay soils, if too much magnesium is present
Dolomite Lime Uses
Dolomite lime eventually reduces soil acidity to the same degree that calcite lime does, but it takes much longer to accomplish this same work. This is one reason why dolomite lime is typically reserved for specialized purposes and is not usually best for home and garden use.
The best case for dolomite lime use is when soil is magnesium deficient. If the ratio of calcium to magnesium in the soil is 6:1 or greater, then your soil is magnesium deficient. In these conditions, plants and grass will grow weakly, will yellow, and will not develop deep roots. Applying calcite lime to magnesium-deficient soil will only aggravate this problem. Dolomite lime can, however, correct magnesium deficiency.
The magnesium content in dolomite lime can make its application trickier. If soil isn’t magnesium deficient and dolomite lime is applied, it may cause soil hardening and compaction. This compaction discourages plant growth and requires nitrogen treatment to undo. Soil compaction due to dolomite lime is most common in clay soils, so it’s generally best to avoid dolomite lime use if your soil contains clay.
Difference Between Dolomitic and Calcitic Lime
Calcite lime and dolomite lime are both derived from limestone, but calcite lime contains higher calcium levels. Dolomite lime contains less calcium but on the flip side contains magnesium, which is rarely present in calcitic lime. This may seem like a small difference, but it makes an impact.
While dolomitic and calcite lime both lower soil acidity with the same effectiveness over a multiyear period, calcitic lime is absorbed into the soil in 2–3 weeks, while dolomite lime can take several months to penetrate the soil. Not only that, but dolomite lime can cause soil compaction if used improperly. These reasons make calcitic lime the best choice for home and garden applications—you’ll see fast results with low risk. Dolomite lime is best reserved for use only when your soil is magnesium deficient, as determined by a professional soil test.