Back to School: Time for a Soil Test?

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Any successful gardener in this area will tell you that the key to a beautiful lawn or garden starts with healthy soil. The only way to ensure your soil is healthy is to conduct a soil test. Soil test results guide decisions like which type of fertilizer to use and whether or not to apply lime. Different types of plants have different pH and nutrient requirements. By soil testing, you can ensure you are applying the proper amounts for optimal growth of all your plants.

 Dirt is inert, soil is a living organism

Okay, no more dirty jokes. But it is true that your soil is alive, which makes it an ideal growing medium for plants. Healthy soils contain a balance of mineral components, plant nutrients, organic matter, air space, and water. Soil test results will give you information on the nutrients present in your soil, particularly nitrogen, phosphorous, and potassium, the nutrients plants need in the highest levels to grow well. Each of these nutrients has its own role in supporting plant development. Nitrogen promotes new leaf growth, while phosphorous helps with root, flower, and seed growth. Potassium promotes plant health, drought and cold tolerance, and flavor development in fruits.

 Without knowing the soil’s fertility or pH level you are more likely to apply too much or not enough fertilizer, which can stress plants, opening them to attack from plant diseases and pest insects. A soil report is the only accurate way to ensure you are delivering the right amount of nutrients for your lawn, garden, and landscape.

pH is also vital to plant growth

Another critical component of soil is the pH, which measures how acidic or alkaline the soil is. Soil pH is important because it can affect the availability of nutrients to your plants. When the pH is too acidic (under 5.5) or too alkaline (over 7.0), certain nutrients chemically bind to soil particles, making them unavailable to plants. Soil pH levels are extremely variable in southeastern North Carolina, ranging from very acidic (as low as 4.0) to moderately alkaline (up to 8.5). Lime is used to raise pH is acidic soils, but is often applied unnecessarily.

 Having the correct soil pH is critical for plant growth. Some plants, such as blueberries, azaleas, and centipede grass, require acidic soils with a pH of 5.0 to 5.5. Most vegetables and other warm season grasses, including Bermuda and zoysiagrass, do better in soils with a pH of 6.0-6.5. If soil pH is above or below the preferred range for a plant the result is plant stress, which increases susceptibility to insect and disease issues that can ultimately lead to decline and even plant death. Soil testing is the only way to accurately determine your soil pH.

 How to take a soil sample

Boxes and forms for soil sampling are available from your local Extension office. When collecting samples, take separate samples from each different area of your yard. For example, collect separate samples from your lawn, vegetable garden, flower borders, and shrubs beds. From each area, collect four or five small samples. Combine these subsamples to fill a separate soil test box for each area.

 Completed samples can be mailed to the NC Department of Agriculture Agronomic Division in Raleigh, or dropped off at your local Extension office. Results are posted on the Agronomic Division’s website, The current turnaround time for soil reports is about two weeks. This can increase to two months or more during the peak season, December through March.

New peak-season soil test fee

Soil samples can be taken any time of the year for analysis. Historically, soil reports have been free for North Carolina residents, but as of this year, all soil samples submitted during the peak season months (December – March) will be charged a $4 processing fee per sample. Getting your samples in now will avoid this fee. Having your soil test results in hand before the spring season gives you more time to amend your soil, lowering the last-minute scramble to get your soil ready for spring planting.

 Learn More!

For help interpreting your soil report, visit, where you can post your questions via the ‘Ask an Expert’ link, or contact your local Extension office. If you live in Pender County, call 259-1235. In New Hanover County, call 798-7660. In Brunswick County call 253-2610.

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