What is one of the most helpful resources to use when establishing or maintaining a garden bed, lawn, landscape, or cultivated field? A soil test! For relatively little cost, soil testing labs provide invaluable information for homeowners, gardeners, and farmers by pinpointing nutrient needs and providing fertilizer recommendations or corrective actions for sampled soils.
Why should you test soil? There are four main reasons to test your soil: 1.) to guide plant selection 2.) to maintain proper soil fertility 3.) to diagnose plant problems and 4.) to follow industry-accepted management practices, such as those used for tree care or for agronomic crop production.
What does a soil test measure? A basic soil test provides information on soil properties including soil pH, cation exchange capacity (CEC), base saturation, lime requirement index, and levels of phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg). Additional tests can measure soil texture and the amount of copper (Cu), iron (Fe), manganese (Mn), zinc (Zn), soluble salts, nitrates, and organic matter in the soil.
Why is soil pH important? Knowing your soil pH is a cost effective way to match a plant’s pH requirement with that of the soil in which you are planting. Soil tests provide a pH value from 1 to 10, though soil pH rarely measures below 3.5 or above 9. Soil is considered acidic when it measures less than 7.0 and alkaline when it measures more than 7.0.
Many plants grow in a wide range of soil pH levels, while others have more specific requirements. For example, numerous ornamental flowering plants, fruits, vegetables, and turfgrass species grow well when the soil pH ranges from 6.2 to 6.8. Other plants such as pin oaks, azaleas and blueberries require a more acidic soil (5.5 to 6.5) to thrive in our area. When grown in a higher pH soil, they tend to exhibit nutrient deficiency symptoms such as leaf yellowing and/or stunted growth.
When should soil be tested? With the growing and harvesting season winding up in NW Ohio, now is a perfectly good time to soil test. Soil testing can be done throughout the year as long as the soil is workable to collect a sample. Since soil test results are used in planning what needs to be done with a specific growing area, they should be taken with ample time to evaluate and act upon the recommendations. Fall is an excellent time to make lime applications to raise soil pH, while spring is best to apply sulfur to lower soil pH.
How often should should soil be tested? For most garden, landscape and agronomic purposes, soil testing every two to three years is adequate to maintain soil fertility. More frequent sampling may be required when diagnosing plant problems or for nutrient-hungry plantings.
Where can soil be tested and how do you interpret results? While Ohio State University no longer provides soil testing services, we do provide soil sampling kits from Penn State University for $10 at the Extension office. After you collect and mail your sample to the lab, recommendations on how to improve soil fertility based upon the desired plants or crops to be grown will soon follow. While many online resources can help explain soil test results, you may also bring or email soil reports to the extension office for further interpretation.