Clemson Lime Rate Calculator

The Clemson Lime Rate Calculator is built for soil test results from the Clemson University Soil Testing Laboratory, which uses the Adams-Evans buffer method; the agricultural limestone rates it calculates are applicable to those results, for field, home, garden, lawn, and ornamental applications. It is published by Clemson Cooperative Extension and the Clemson University Center for Agricultural Technology.

What it calculates

Enter the soil pH and buffer pH from your soil test report, then set a target pH — directly, or by selecting a crop group — and a mixing depth. The calculator returns the pure lime requirement, reported in pounds per acre, pounds per 1,000 square feet for home, garden, lawn, and ornamental applications, and kilograms per hectare.

Describe one or more lime products to convert that pure requirement into the amount of a real material to buy and spread. Choose a lime material from the catalog, enter your own calcium carbonate equivalent and fineness, or enter a relative neutralizing value directly if that is what your dealer supplies. Add material, delivery, and spreading costs and the results compare the sources side by side, so the cheaper product per ton is not mistaken for the cheaper product per acre.

Reading the results

Calcium carbonate equivalent and fineness are measures of a product’s neutralizing capability and are normally available from the dealer. Together they give the relative neutralizing value, which is what actually determines how much of a given material equals the pure lime requirement. A coarse or low-purity product needs a higher rate to do the same work.

Soil test recommendations from Clemson assume a mixing depth of 8 inches. For ornamentals and turf grass, where no tilling is performed, select a 4-inch mixing depth here and apply to the surface in two applications six months apart — or, working from your soil test report directly, apply half the recommended lime now and the remainder in six months.

Limits

This calculator does not replace the recommendations printed on your soil test report; it lets you adjust the target and mixing depth when your situation differs from the one the report assumed. Proper liming is essential for optimizing nutrient availability, and over-liming can be as detrimental as under-liming.