Understanding Soil Testing: Beyond Nutrient Deficiencies in Gardening

By Trish Svoboda

Many gardeners believe that soil testing solely identifies nutrient deficiencies; however, these tests also aid in assessing whether the soil has sufficient nutrients. Fundamental tests examine the soil’s pH, as well as its phosphorus and potassium levels.

“Most of the lawn and garden soil tests that come out of our soil-testing lab show more than adequate levels of both phosphorus and potassium,” said Kansas State University horticultural expert Cynthia Domenghini. “If those nutrients are not needed, applying them is a waste of money and can be a source of pollution.”

Domenghini advises gardeners to conduct soil tests before starting spring gardening, especially if the soil has not been tested for several years. A soil test will determine fertility problems and should be utilized to identify nutrient deficiencies.

Other factors that can affect the growth of plants that cannot be identified with a soil test include:

· Not enough sun

· Poor soil physical characteristics

· Walnut trees (walnuts give off a natural herbicide that interferes with the growth of some plants, such as tomatoes).

· Tree roots.

· Shallow soils.

· Improper watering.

· Overwatering.

· More information on taking an accurate soil test is available online from the K-State Agronomy Soil Analysis.

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