Soil Sampling for Gardeners

— Written By Tamara Carawan
en Español

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garden trowel and soil sampling box

It is spring and many folks are beginning their annual gardening traditions. One important task that gardeners can perform right now is to conduct a soil test. Without a soil test, it is difficult to make recommendations for improving soil fertility because there is no reference point from which to start.

The North Carolina Department of Agriculture and Consumer Services Agronomic Division provides this service to all N.C. residents. Upon completion, samples are available online through the Public Access Laboratory System (PALS). Sample reports are generally easy to read, but if you need assistance interpreting results, please contact the Extension office.

Since plants cannot move, they must use their roots to search out nutrients in soil. Within soil are 14 essential nutrients that plants require. The other three nutrients, oxygen, carbon, and hydrogen, are found in water and air. If one of these nutrients is lacking, plant growth will decrease, no matter if other nutrients are provided in abundance. A soil test will help to identify nutrient deficiencies and offer recommendations to optimize growth.

Soil pH is another important measurement that is provided with a soil test. Soil pH affects the availability of soil nutrients, which might become inaccessible or toxic if soil pH is too low (acidic) or too high (basic). A soil test will identify a pH range for your specific crop and offer recommendations if adjustments are needed.

To complete a soil test, you must first collect 10-20 small, random samples from your yard or garden, from a depth of 4-6 inches (a core or slice of soil from the surface to the specified depth). This is best achieved by walking a pattern across the sample area and randomly collecting samples along the way. These samples are then mixed together to represent the larger area and placed into a sample collection box. This box requires your name, address and sample ID, which will correspond to a sample submission form that will accompany the sample during submission.

Sample boxes and submission forms are available through my office and I can assist with the collection process if needed. Sample reports should be available in about one-week in the spring, but several weeks may be needed during winter months. Samples should be mailed to the Agronomic lab using the address provided on the form. For more information on completing this submission, review the NCDS&CS sample instructions.

Liming recommendations should be sufficient for 2-3 years and fertilizer recommendations provide all the nutrients required for the single growing season of the specified crop.

Before we get too far into the spring, take the time to consider a soil sample. Soil sampling is a cheap and effective tool to help maximize plant health and growth. If you would like more information about this subject, please contact Daniel Simpson at (252) 745-4121 or send me an email at