Testing Your Soil's Fertility
(Conservation Currents, Northern Virginia Soil and Water Conservation District)
Nearly year-round, the Conservation District gets calls from homeowners interested in having their soil tested in their lawns or gardens. The District doesn’t have the staff or equipment to analyze your soil, but Virginia Tech does. The Virginia Tech Soil Testing Laboratory is a part of Virginia’s Cooperative Extension. The routine soil test is all one normally needs for a fertility evaluation. Soil samples are analyzed and computer recommendations are generated usually within three working days of receipt.
All Fairfax County public libraries have a supply of Virginia Tech soil testing kits. The kits have instructions on how to collect the sample and where to mail it for analysis. The fee for a routine analysis is $10.00. A routine soil test package includes analyses for soil pH, phosphorus, potassium, calcium, magnesium, zinc, manganese, copper, iron and boron, along with fertilizer and lime recommendations for specified plants. Soluble salts and organic matter tests are also available for an additional fee.
Why test your soil?
Plants can produce their own energy but require a fertile soil to supply needed nutrients. Healthy, well-fed plants are better able to withstand diseases and insects and to compete with weeds. For a few dollars a chemical soil analysis can check your soil’s fertility and determine if any corrective action is needed.
A soil test is the best tool available for determining the lime and fertilizer needed for the best economic and environmental production of gardens and healthier, more beautiful lawns. Testing the soil takes out the guesswork and prevents you from under or over liming and fertilizing. Over-fertilization is costly and may be damaging to the environment.
You can take a soil sample any time of the year; however, it is best not to sample when the soil is extremely wet. The number of samples needed from a particular area depends on the uniformity of the soil and its past treatment.