Agricultural Soil and Plant Testing

Home Soil-Test Kits

• Most home pH test kits are designed to be used with acid soils. In alkaline soils, with pH values above 7.0, the values are not accurate enough to be of significant value. If you know or suspect that your soil is alkaline, have your soil professionally tested. Professional tests are usually very inexpensive through your local agricultural extension.

Taking a Soil Sample

• Soil tests can be run at any time, but the best time is in the fall when preparing the garden bed for the winter. Take approximately 1 cup of soil from several spots spread over your garden. Mix the soil together in a bucket and remove 1 cup of the mixed soil for testing. Allow the soil to dry, then package it in a plastic bag and seal it. Label the bag, indicating where the sample came from. Run a separate sample for areas with poor plant growth or different types of soil.

What the Test Analyzes

• Your soil pH test results will tell you the pH of your soil and make recommendations for correcting it with suggested amounts of lime to add if needed. Additional tests are usually available, sometimes for an extra fee, that give you information on your soil fertility and fertilizer requirements including nitrogen, phosphorus, potassium, calcium and magnesium values. Many tests also provide information on toxic elements that may be present in your soil. If you need information on soil pests and diseases, you will need a separate test. Ask your agricultural extension agent what information is available in your area.

Using Soil Test Results

• Your soil test results may suggest the addition of lime or fertilizer. These recommendations may be in the form or tons per acre or lbs. per 1,000 square feet. One ton of limestone per acre is equal to 5 lbs. per 100 square feet. You will need to test the soil again every two years and follow the directions on your most recent soil test. Add lime one time only, unless your results indicate otherwise. Fertilizer amounts are added every growing season.

Plant Testing

• Plant testing is a valuable tool for diagnosing problems with specific plants. The analysis gives you information about nutrient deficiencies that exist in the plant so that you can correct them. If you have problems with a specific plant, it is often helpful to run a test on the problem plant and a nearby healthy plant. Tests are usually run by your local County Extension Service. Results are even more valuable if a soil sample is run at the same time, to give you as much information as possible.