Calcitic lime is a soil amendment made from ground limestone that is primarily calcium carbonate (CaCO₃). It’s the most common material used to raise soil pH, making acidic soil more neutral so plants can access nutrients more effectively. Pure calcitic lime contains close to 100% calcium carbonate, though commercial products typically range from 85% to over 98% depending on the quality of the limestone deposit.
How Calcitic Lime Differs From Dolomitic Lime
The two liming materials you’ll encounter most often are calcitic and dolomitic. The difference comes down to magnesium. Calcitic lime is derived from deposits of primarily calcium carbonate with little magnesium. Dolomitic lime comes from deposits that combine calcium carbonate with magnesium carbonate, giving it much higher magnesium levels.
If a soil test shows your magnesium levels are low, dolomitic lime addresses two problems at once. If magnesium is already adequate, calcitic lime is the better choice because adding excess magnesium can interfere with how plants absorb calcium and potassium. Your soil test results will typically recommend one or the other.
How It Neutralizes Soil Acidity
Acidic soil has a high concentration of hydrogen ions, and the carbonate portion of calcitic lime is what actually neutralizes them. When calcium carbonate reacts with those hydrogen ions, it produces water, carbon dioxide, and free calcium. The hydrogen ions are consumed in the process, which is what raises the pH.
This is an important distinction: it’s the carbonate doing the neutralizing, not the calcium itself. Products that contain calcium in other forms, like calcium chloride or calcium sulfate (gypsum), won’t change your soil pH at all. The hydrogen ions remain even after those products dissolve. To raise pH, you need a material that contains carbonates, oxides, or hydroxides.
What Calcium Does for Plants
Beyond correcting pH, calcitic lime supplies calcium, which is an essential plant nutrient. Calcium plays a structural role in cell walls and cell membranes, giving plant tissues their rigidity and strength. Without enough calcium, fruits and vegetables are prone to physical problems. Tomatoes, cherries, and apples can develop cracking when their cell walls lack sufficient calcium to handle changes in moisture from rain or humidity swings.
Calcium also functions as a chemical messenger inside plant cells, helping coordinate responses to environmental stress and developmental signals. Plants absorb calcium from the soil solution through their roots and move it upward through the water-conducting tissue in their stems. Once calcium is deposited in older leaves and fruits, the plant can’t redistribute it, which is why a steady supply in the soil matters throughout the growing season.
Measuring Lime Quality With CCE
Lime products are graded using a standard called Calcium Carbonate Equivalent, or CCE. Pure calcium carbonate is assigned a CCE of 100%. This gives you a way to compare different products on an apples-to-apples basis. A calcitic limestone from one quarry might test at 100.9% CCE, while another from a different region could come in at 85.2%. The higher the CCE, the more neutralizing power per pound.
Fineness also matters. Coarser particles react more slowly with the soil, so two products with the same CCE can perform differently depending on how finely they’re ground. Most state soil labs factor both CCE and particle size into their lime recommendations.
Pelletized vs. Pulverized Forms
Calcitic lime is sold in two main forms: pulverized (a fine powder) and pelletized (small granules). Pelletized lime is just finely ground limestone held together with a water-soluble binding agent. Once it gets wet in the soil, the pellets break apart into the same fine particles you’d get from pulverized lime.
There’s no difference in effectiveness between the two. Pelletized lime is less dusty and easier to spread evenly with a standard lawn spreader, which is why it dominates the lawn and garden market. Pulverized lime costs less per ton and is the standard choice for agricultural fields, where specialized equipment handles the dust. For a home lawn or garden, pelletized is usually the more practical option.
How Much to Apply
The amount of lime you need depends on your current soil pH, your target pH, and your soil type. Sandy soils need far less lime than clay soils to achieve the same pH change. University of Georgia data illustrates the range: raising pH by one full point across the top 8 inches of soil can require anywhere from about 1,000 pounds per acre in a sandy soil to 10,000 pounds per acre in a heavy clay. For a home lawn, that translates to roughly 23 to 230 pounds per 1,000 square feet, which is why a soil test is essential before you start spreading.
Most soil testing labs provide a specific lime recommendation in their results, already adjusted for your soil’s texture and buffering capacity. Applying lime without a test is guesswork that can easily overshoot, and overlimed soil creates its own set of nutrient problems.
How Long It Takes to Work
Calcitic lime is not a quick fix. It often takes a year or more before you can measure a meaningful change in soil pH, even under ideal conditions. The reaction requires moisture, so dry soil slows things down considerably. In cases where soil pH is extremely low, you may notice a response within weeks, but that’s the exception rather than the rule.
For best results, apply lime several months before the growing season when you most need the pH correction. Fall applications give the lime time to react through winter and early spring rains. Working lime into the soil speeds up the process compared to surface application, since it brings the calcium carbonate into direct contact with the acidic soil particles below.