Lawns require a specific pH range in which to grow, usually between 5.8 and 7.0. This ensures that essential nutrients remain available and that grass remains healthy. When soil is too acidic, you may need to add lime to correct the problem. There are several types of lime you can use. Dolomitic lime, while very effective, is one of the slowest.
Often folded under the umbrella term “agricultural limestone,” dolomitic lime is a type of ground limestone composed of calcium carbonate. It is distinguished from calcitic limestone only in that it also contains magnesium in the form of the compound dolomite, usually 6 percent or less. Thus it is well suited to application on lawns that require not only a higher pH but also an infusion of the element magnesium.
Rate of pH Change in Soil
Dolomitic lime, along with its close cousin calcitic lime, affects the pH of soil relatively slowly. Although timing depends on factors like soil type and starting pH, it can take several months to see a change in soil acidity and even longer to see a full correction. Often, if your soil is very far-gone, so much lime is called for that you can’t even apply it all at once without risking damage to the lawn. In that case, you have to break up the lawn applications into two parts, spring and fall (or vice versa).
Faster Types of Lime
If you want quicker results, you can try pelletized lime, hydrated lime or burned lime, all of which raise soil pH considerably faster than dolomitic lime does. Athough these limes work faster, they have drawbacks. Burned and hydrated lime types are dangerous to work with, as they can burn your hands as well as the lawn. When applying them, be sure to wear gloves and water in lime thoroughly to prevent foliar damage. Pelletized lime isn’t hazardous, but it is expensive.
How much lime you add depends on several factors: soil type, starting pH and target pH (which depends on your turfgrass species). A soil test will tell you what your current pH is, and then you can calculate the amount of lime to add. Generally, you need more lime for clay soils than loam, and more for loam than sandy soils. If, for instance, you wanted to raise 1,000 square feet of loamy soil from a pH 5.5 to 6.0, you would need 25 pounds of lime. Don’t apply when the ground is too wet, or lime may clump. Don’t apply when frosty or frozen, as you risk burning the lawn.
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