Is Calcium Carbonate Good for Lawns?

Lime

• Calcium carbonate is also known as lime. The process of adding it to grass is commonly referred to as liming the lawn. The amount of calcium carbonate in a bag of lime can vary. Most lime sold for home use is not pure calcium carbonate. You need to know how much calcium carbonate is included so that the right amount can be applied. Read the bag label for the "calcium carbonate equivalent." The number indicates what percentage of the lime is pure calcium carbonate. For example, if the packaging indicates a calcium carbonate equivalent of 60, the content is 60 percent calcium carbonate.

Soil pH

• Calcium carbonate, or lime, is used to adjust the pH, or acidity, of the soil so that it is at the ideal level for growing grass. It is good for lawns growing in soils that are acidic since it increases the soil pH and reduces acidity. Calcium carbonate is not good for soils that have a pH that is too high for grass since it will continue to increase the pH. For most lawns, a pH between 6 and 7 is ideal.

Soil Testing

• The soil should be tested before calcium carbonate is applied. Testing will reveal whether the lawn needs liming or not. Home soil testing kits are available from nurseries or garden supply centers. Many cooperative extension offices also offer soil testing services at no charge. Test results will reveal the pH level of the soil. A disadvantage of home tests is that they will not indicate how much lime is needed to correct the pH. A complete soil test from a cooperative extension office will reveal whether calcium carbonate is necessary to balance the acid level in the soil, and, if so, how much should be applied.

Problems Caused by Improper Soil pH

• The wrong soil pH for a lawn -- whether it is natural, a result of the application of too much or too little calcium carbonate or the application of too much fertilizer -- will quickly weaken the grass. When the pH is too low or too high, the lawn can't take up necessary nutrients like nitrogen, potassium or magnesium. The grass will begin to lose its color and its ability to resist pests and disease. Using calcium carbonate to correct the pH can help restore a lawn to health as long as it is used in conjunction with soil tests to ensure the soil pH is actually corrected.