How to Test Your Soil

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If you want to grow healthy food, you want to start with healthy soil, and a soil test is an inexpensive way to do just that. If you are growing in the ground, testing can maximize productivity, protect you and the environment, and should be the first thing done before planting your first seed, says Kymisha Montgomery, urban agriculture coordinator at the Civic Garden Center. “If you’re not focusing on what’s feeding your plants, then you are missing the whole point,” she says, noting that testing isn’t as necessary with raised beds because the gardener would be creating their own soil composition.

A standard soil test measures soil pH and the level of phosphate, potassium, magnesium, and calcium in the soil. Penn State Extension Office offers mail-in testing for $10 and offers recommendations for reaching optimum soil health.

Other kinds of soil tests can be performed for additional fees, according to the Ohio State Extension. A textural analysis determines the percentages of sand, silt, and clay in the soil, which is useful because soil texture impacts nutrient retention, root growth, water movement, and other factors.

Further testing should be considered based on your situation. Beyond the standard test, the Ohio State Extension Office recommends an initial assessment of soil texture, salinity, and micronutrients if plants are being grown in a new area with no prior history of fertilizer use or soil amendments. If heavy metal toxicity is a concern, a soil test for heavy metals is recommended.

Three good reasons to test your soil:

• Safety. The whole reason you’re growing healthy food is to become more healthy, says Montgomery. Cincinnati has an industrial past, and therefore testing for heavy metals might be wise. The Hamilton County Health Department provides free lead tests for soil, and OSU charges $18 for heavy metal testing that includes lead, arsenic, and cadmium. Other heavy metals of greatest concern include chromium, nickel, mercury, and molybdenum.
• Know what to grow. Different varieties of plants thrive in different types of soil. Brassicas (broccoli, cabbage, kale, and turnips) like a higher concentration of nitrogen, for example, while sweet potatoes like low soil acidity. Soil samples can be tested any time of year, as long as the soil is workable. Remember to use fertilizers when conditions are appropriate; apply lime in the fall, for example, and sulfur in the spring.
• Save money and time. A soil test tells you what you need instead of using unnecessary fertilizers. Significant amounts of essential nutrients are removed from the soil through plant growth, so consider leaving clippings and fallen tree leaves on the ground to decompose. This also creates a natural habitat for insects during winter months.