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Soil Testing FAQs

Posted: March 8, 2012

Now that spring is in the air, many people have been stopping in to the Extension office to purchase a soil test kit. Here are answers to some frequently-asked questions about soil testing.

Q:  Why should I test my soil?

A:  Proper soil fertility is an essential component of good plant health. The part of plants that we see aboveground is only as good as the part we don’t see – the roots; and the roots are only as good as the soil in which they’re growing. Roots rely on soil to obtain key nutrients. It’s impossible for a person looking at a soil sample to know what levels of nutrients the soil contains; the only way to know is by doing a soil test. Guessing about nutrient levels and nutritional needs can be wasteful of your time and money, harmful to the environment, and detrimental to your plants, if you are applying excessive or unneeded fertilizers.

Q:  Where can I get a soil test kit?

A:  Penn State soil test kits are available at every county Extension office. The kit contains a soil sample bag, sampling instructions, a submission form, and a mailing envelope.  You may also go to the Penn State Agricultural Analytical Services Lab website at www.aasl.psu.edu, print out the soil fertility sample submission form, and then submit a sample in your own container and mailing envelope, along with the form and payment.

Q:  Do I bring the soil to the Extension office?

A:  No; you just purchase the soil test kit at the Extension office. The kit includes detailed instructions on sampling and preparing the soil, which is then mailed by you to the Penn State Lab in the mailing envelope provided.

Q:  How much does the Penn State soil test cost?

A:  The standard soil fertility test kit costs $9.00. Your only additional cost is the postage to mail about 1 cup, or 8 ounces, of the soil sample to the lab at University Park in State College. The $9.00 cost covers measurement of soil pH and the levels of the plant nutrients phosphorus, potassium, calcium, and magnesium. You’ll receive a written report with the chemical analysis of the soil, along with lime and fertilizer recommendations for the specified crop. For most home garden situations, the standard test is sufficient. Optional tests, for soil characteristics such as organic matter, soluble salts, and particle size, are available for an additional fee, for which you send a check or money order along with your sample submission.

Q:  What about nitrogen? Isn’t that an important nutrient for plants?

A:  Yes, nitrogen is a critical element for plant growth, but the standard soil analysis does not test for the nitrogen level. That’s because nitrogen is an extremely mobile nutrient that can move quickly through the soil and is used in such large amounts by the plant during the growing season, it would be difficult to achieve an accurate measurement. The written report still includes a nitrogen recommendation, though, based on that specific plant’s nitrogen needs for that growing season.

Q:  How many kits do I need?

A:  You should purchase a separate kit for each different garden area, such as lawn, flower garden, vegetable garden, and fruit orchard. If your lawn is visibly different in different areas of your property, such as having very different soil traits or drainage patterns, you should purchase a kit for each area. For an ornamental or fruiting tree growing in a lawn or garden bed, the Penn State fertilizer recommendations for that lawn or garden area will meet the nutritional needs of that tree.

Q:  Why do I need a kit for each different garden area?

A:  The Penn State lab tailors its fertilizer recommendations for the crop that you indicate on the form, either to grow or to maintain. Grass, flowers, ornamental trees, vegetables, and fruit trees all have differing nutrient needs that may vary also if you are either just starting to grow the plant or trying to improve its growth.

Q:  I think my neighbor sprayed my plants with weed killer. Will the lab test for this?

A:  No, the Penn State Lab does not test samples for pesticide residues, gas, oil, or unknown substances. It can do optional analyses for certain elements and contaminants that may be found in soil, such as lead, arsenic, mercury, and PCBs, for additional fees. If you want any of these tests done, the submission form includes a place where you can indicate which ones, the associated cost, and instructions for mailing your payment along with the sample.

Q:  How long does it take to get results?

A:  Generally, depending on how busy the lab is, you should receive your written report in about 2 weeks.

Q:  How often should I do a soil test?

A:  Penn State recommends soil testing every three to four years for lawns and gardens.

Q:  I received my written report, but I don’t understand it. What do I do?

A:  You may bring your written report in to the Extension office, and someone can help you interpret it. Even easier, you may call the Extension office, and given the five-digit serial number from the report, an educator can pull it up on his or her computer and go over it with you by telephone. The specific recommendations, and the assistance we can provide you in interpreting the results, are two great reasons to use Penn State’s soil testing kits for your home garden and landscape.