Learn how to test your soil for pH and basic nutrients. Once you know what kind of soil you are working with, you can amend the soil so your lawn and garden flourish.
What is Soil?
Soil is made up of minerals, organic matter (living and dead), air and water. Soil provides nutrients and serves as a foundation for plants. Improving your soil increases plant health and is critical to growing a lawn or garden you’ll enjoy for a lifetime.
Importance of a Soil Test
Plant growth and vigor are often dependent on soil pH—the measurement of how acidic or alkaline the soil is. Soil pH is measured on a scale of 1 to 14 with a measurement of 7.0 considered neutral. A number below 7 is acidic (sometimes called “sour”); a number above 7 is alkaline (“sweet”). Most plants prefer nearly neutral soil with a pH between 6.2 and 7.2. Some (such as azaleas) prefer a more acidic soil.
A soil test determines whether your soil is acidic, neutral or alkaline. A soil test also indicates which elements are missing from your soil and how much to add to remedy the problem. Soil test kits are available at Lowe’s Garden Centers. These kits will provide an immediate analysis of your soil’s pH and nutrient levels. In addition, you can find testing meters that measure pH as well as moisture and light.
Your local cooperative extension office can test your soil sample for pH and nutrient levels (some states charge a small fee). The soil analysis usually takes a few weeks to process. The analysis includes detailed results and suggested amendments specific to your region.
Home soil test kits include vials and tablets to test your soil, as well as a chart to interpret the results. With testing meters, you simply insert the meter probe into the soil and read the results. Follow the manufacturer’s instructions for these home-testing solutions.
To prepare a soil sample to send for analysis, you’ll need a clean bucket, a garden trowel and a clean plastic (not metal) container. The steps are simple, but they should be followed carefully to get an accurate reading.
Be sure to take the sample when the soil is fairly dry—wet soil can give a false test reading. You may want to check your soil more than once to verify your results.
Soil can be tested at any time, but fall or early spring is preferred because it allows time to make adjustments before planting.
Most native soils in the eastern United States are naturally acidic. Alaska, Hawaii and parts of the Pacific Northwest tend towards acidic soil as well. Acidic soil is a good environment for thatch, weeds and diseases and also reduces the effectiveness of your fertilizer or herbicide.
Garden lime, or limestone, is the soil amendment usually recommended for reducing soil acidity. Lime also is a natural source of calcium and magnesium—elements necessary for healthy plant growth. Correction of an overly-acidic soil is a long-term project that takes time to complete. Fall is the best time to apply garden lime, but it can be applied any time of year.
When using lawn-care products or soil amendments, always follow the package directions regarding proper clothing, protective equipment, application procedures and safety precautions.
Alkaline soils are most common in the central and southwestern United States, which are generally areas with less rainfall. Alkaline soil restricts a plant’s ability to take in nutrients (such as iron).
Applying soil conditioners with sulfur or gypsum are the most common amendments. Sphagnum peat moss is an organic, naturally acidic alternative; however, it may not be cost-effective to apply to large areas. Organic compost can increase soil acidity if applied regularly.
Rather than trying to make wholesale changes to your soil’s pH, consider raised beds for flower or vegetable gardening. With raised beds, you customize the soil mix to match the needs of your crop.