How do I get my soil tested?
There are many different kinds of soil tests.
Just like when you go to the doctor, and they can test your blood pressure or your vitamin levels or whether you have a particular kind of infection, there are many different soil properties that a lab can test.
The most common soil tests you might be looking far are soil fertility tests, soil contaminant tests, and soil health tests. This FAQ currently focuses on soil fertility tests.
For information about soil contamination testing, see this recorded webinar.
An important note about soil fertility test recommendations
A soil fertility test tells you about your soil's ability to provide essential nutrients to plants. The test results will help you decide how much fertilizer or other soil amendments to apply to improve your plant's growth. If you are gardening as a hobby, you can use the fertilizer recommendations in your test results. But, if you are farming crops for sale, you will need to send your soil test results to a certified planner. This is because, in Maryland, if you are a farmer who sells $2,500 or more of farm products, or who has 8,000 lbs or more of livestock, you are legally required to follow a nutrient management plan written by a certified planner. More information about this regulation is available from the Maryland Department of Agriculture Nutrient Management Program, and the UMD Agricultural Nutrient Management Program.
Do you need a soil fertility test or a growing medium analysis?
Next, to find an appropriate testing laboratory, you will need to determine whether you are growing in soil or a created growing medium. A created growing medium is considered a material that was made from at least two components which can include any organic material like compost. A created growing medium is not a soil amended with compost. Urban growers frequently call any material they grow in "soil," but when you decide what soil test to order, it is important to distinguish between naturally-occurring mineral soils and created growing media.
Mineral soils are made of sand, silt, and clay that forms over time from the native parent material (rock). There is also some naturally occurring organic matter in the soil, typically between 1 and 5 % depending on the land-use.
Many urban growers add large amounts of compost or wood chips on top of their native soil, or grow in raised beds or containers filled with compost. When you are growing in a material that is more than 50% added organic materials ("organic" as in made of carbon-rich organic matter such as compost, peat moss, etc.), that is considered a created growing medium or an organic-based growing medium. If you have questions about telling the difference between a soil or growing medium, contact your local Extension Educator for technical assistance.
If you are growing in a mineral soil, a standard soil fertility test will tell you about the ability of your soil to provide nutrients to plants.
If you are growing in an organic-based growing medium, we recommend you ask the laboratory for a soilless growing media analysis (also called a saturated media extract). This recommendation is because a fertility test designed for a mineral soil uses an extraction method that is too strong for a growing media made of organic matter like compost. A standard soil fertility test will overestimate the nutrient availability from an organic-based growing medium.
Lists of testing labs
For home gardeners and community gardens, the University of Maryland Extension Home and Garden Information Center has a very helpful webpage on soil testing, with a video showing you how to collect a sample, a list of testing labs, and a series of FAQs.
For professional farmers, the University of Maryland Extension Agricultural Nutrient Management Program has this webpage on soil testing. Their webpage has instructions for soil sampling and lists comparing soil and growing media test labs (see tabs at top of the table for different kinds of tests).
Once you have determined which kind of test you need, and selected a testing lab, check that lab's website or call their main desk to get a copy of their sample submission form. They will have different forms for different soil tests. You will need to clearly label your samples and mail them to the lab with a copy of the sample submission form. Depending on the lab, you might be able to pay for the testing online, over the phone, or by check mailed with the sample.
Back to Frequently Asked Questions
FAQ written by Neith Little, with input from Dr. Andrew Ristvey, Emileigh Lucas, and Craig Yohn.