Dolomite - Soil Conditioner
What Is Dolomite Used for With Plants?
Dolomite, a type of limestone, provides valuable nutrients to plants and helps change the pH of the soil by raising it to match the plants' needs. It's sometimes called dolomitic lime or dolomitic limestone, and provides more nutrients than straight lime. It's often used in addition to balanced fertilizers, particularly with seeding fruit.
What It Contains?
Dolomite is a limestone compound that contains calcium and magnesium. The best mixtures contain 8 to 12 percent magnesium and 18 to 22 percent calcium. These elements help influence the pH of the soil and provide valuable nutrients to plants. Dolomite can often contain sodium, but it should only be 0.2 percent sodium or less. More sodium can change the salinity of your soil, which can kill many plants.
Why Use Dolomite?
Dolomite is best used to change the acidity, or pH, of the soil. Start with a soil pH test to determine the existing pH. Most plants do best with a pH of 6.0 to 7.4. If your soil registers with a pH of 5.9 or below, dolomitic lime can help raise the pH to make the soil more plant-friendly. Some plants prefer acidic soils, where the pH is lower, so check on your specific plants' needs before adding the dolomite. Some plants, especially vegetables that have lots of seeds inside, such as tomatoes (Lycopersicon esculentum), need extra calcium as they grow, and the dolomite is an excellent way to provide that nutrient.
When to Use It?
You can add dolomite to your yard, flower beds and vegetable gardens any time there's no frost or freezing temperatures, but it's best to add it in spring or fall. Pick a day when no rain is predicted so it won't wash off the soil before being absorbed. With vegetables, adding the dolomite before you plant gives the seeds an extra boost, then you can add more as necessary as the plants are growing.
How to Apply?
If you're adding it to an empty garden where you plan to plant flowers or vegetables, turn it into the top 6 inches of the soil before you plant. To change the soil's pH, determine how much you need and spread it on top of the soil. For example, if your soil has a pH of 5.5 and you want to raise it to closer to 6.5, add 10 pounds of dolomite per 100 square feet of space -- that would be equivalent to a 10-by-10-foot bed or a 5-by-20-foot bed. To prevent burning existing plants, spread the applications out throughout the growing season.