Originally Posted by
phreedom_man
Dolomitic Lime
[FONT="]Dolomitic lime lowers the acidity of potting soil mixes, raising
the pH. Commercial and homemade potting soils often contain peat moss. Peat raises soil acidity and many house plants need a more neutral pH to flourish. [/FONT]
[FONT="]Dolomitic lime is a mineral that must be ground or pelletized for houseplant use. Limestone comes in two forms, one mostly calcium while the other contains magnesium. "Dolomitic rock contains at least 6 percent Magnesium oxide,” says David Goforth of the North Carolina State University Master Gardener Program.[/FONT]
[FONT="]Dolomitic lime raises potting soil pH and makes necessary houseplant nutrients more available. Houseplant soil with too low a pH is too acidic. Plant nutrients are chemically bound in the soil and not available to your houseplant. Elements like fluorine or chlorine introduced by tap water become more toxic.[/FONT]
Lime is added according to the amount of potting mix you have. Experts at the University of Georgia Extension use "2 to 3 ounces (dry weight) of dolomitic limestone to 4 gallons (1/2 bushel) of mix" for most plants.
[FONT="]For bulk soil, Aggie Horticulture experts use this basic rule: "Add about 8 pounds of dolomite per cubic yard of potting mix to raise the pH by one unit." In other words if you have pH of 5.5, adding the dolomitic lime would raise the pH to 6.5. They warn that doubling the lime does not raise pH another unit, the pH scale does not work that way.[/FONT]
[FONT="]Dolomite lime requires time to change the pH of soil. Over a space of two to three months, the calcium and magnesium react within the soil to gradually change the pH. In order for lime to be effective on spring-planted tomatoes, it should be added to a garden no later than early spring. Some gardeners prefer to test soil and add lime in late fall. During this time, the wait for a soil test is shorter because many other gardeners have their soil tested in spring.[/FONT]
[FONT="]If tomatoes suffer from blossom end rot, this may be a sign that the soil should be limed. Tomatoes require a slightly acidic pH range between 6.5 to 6.7. In more acidic soil, the plants are not able to take up calcium even if the nutrient is abundant in the soil. But a low pH is usually a sign of low calcium in the soil. Tomato fruit that suffers from the condition begin to rot on their blossom ends.[/FONT]
[FONT="]Although a soil test will tell exactly how much lime to add, generally soils that have not been limed in two to three years should have 2 cups of dolomite lime added to the soil per each tomato plant that is placed[/FONT][FONT="] in the ground. The ground should be broken up to a depth of 12 inches and the lime should be thoroughly mixed into the soil.[/FONT]
