Recommendations for improving soil fertility

Soils compared

The quality of a soil can't be measured solely by examining the color of the sample. Thorough chemical analyses are required for optimum fertility. Photo courtesy the UT Soil, Plant and Pest Center.

It’s no secret on the farm that soil fertility is key to a good crop yield. It’s also no secret that you can’t tell a soil’s components solely by evaluating the color of the samples. Thorough, reliable chemical tests are required.  But how often do you need them?

“The frequency of soil testing can vary depending on cropping intensities, soil types, fertilization rates, tillage methods, weather conditions and new research findings,” said Debbie Joines, manager of the University of Tennessee Soil, Plant and Pest Center. The center
performs basic soil tests that include soil pH, buffer value, phosphorus, potassium, calcium and magnesium for the modest fee of $7.00 per sample. More extensive tests are also available.

Joines offers these general schedules to producers and homeowners who wonder how often they should invest in soil tests: 

1. Continuous Row Crops (conventional) — every two to three years.

2. Double-cropping Systems — every two years.

3. Continuous No-till Soybeans (only) — every three to five years.

4. Continuous No-till Corn or Cotton — every two years.

5. Hay Systems — every two years.

6. High-value Cash Crops (tobacco, vegetables) — annually.

7. Lawns, Gardens and Pasture Crops — every three to five years.

8. Any time a nutrient problem is suspected.

9. At the beginning of a different cropping rotation.

Joines said soil test results are used to formulate research-based, cost-effective lime and fertilizer recommendations specific to the type of crop or plant and yield desired. “Following our recommendations and good cultural practices will enhance yields and therefore help your bottomline,” she added. “For some production practices you will get the best results if you submit your samples in the fall and follow up with recommend fertilization and soil amendments,” she said. “But many folks prefer to submit spring samples, and following any recommended procedures should enhance field performance.”

Procedures for accurately sampling soils from large tracts of land differ from those used for a home lawn or garden. Visit the center’s website: to learn more about collecting and submitting samples. Click on the link for soil testing.  For more information, you may also contact the center at
615-832-5850 or by email or you can contact your local county UT Extension agent.

UT Extension provides a gateway to the University of Tennessee as the outreach unit of the UT Institute of Agriculture. With an office in every Tennessee county, UT Extension delivers educational programs and research-based information to citizens throughout the state. In cooperation with Tennessee State University, UT Extension works with farmers, families, youth and communities to improve lives by addressing problems and issues at the local, state and national levels.



Debbie Joines, UT Soil, Plant and Pest Center,


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