Episode 36: What Millions of Soil Tests Reveal About Soil Fertility
Season 5
Episode 36
November 3, 2026
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Show Notes
Are soils supplying the nutrients crops need? Millions of soil tests from across the U.S. and Canada offer a revealing picture.
In this episode, Dr. Karl Wyant is joined by Dr. Leanna Nigon, director of agronomy and research at The Fertilizer Institute (TFI), to explore findings from the latest TFI Soil Test Summary, drawing on approximately 10.2 million soil samples from across the U.S. and Canada. With more than 40 percent of samples testing below critical levels for phosphorus and potassium, Leanna explains what those thresholds mean for fertilizer decisions and how nutrient needs vary across regions.
They also explore soil pH and soil organic matter levels, why regional averages only tell part of the story and how consistently testing your own fields can help you track changes and plan ahead.
Explore the new data as soon as it’s available: https://www.nutrienttools.org/getting-started/soil-test-summary/
Subscribe to our YouTube channel: https://www.youtube.com/@NutrieneKonomics
"Anything below critical...you can benefit from putting on additional nutrients."
About the Guest
Leanna Leverich Nigon
Director of Agronomy and Research, The Fertilizer Institute
Leanna Leverich Nigon is the director of agronomy and research at The Fertilizer Institute, where she leads the Science and Research Program focused on 4R Nutrient Stewardship. In her role, she works to connect research with industry needs, creating tools and resources to support farmers and the overall fertilizer sector. She has a background and research expertise in soil fertility, geographic information systems and machine learning for nutrient management. She holds a bachelor’s degree in agronomy and communications from the University of Wisconsin-Madison and a master’s degree and Ph.D. in soil science from the University of Montana-Twin Cities. She grew up on a cash crop farm in Wisconsin and currently resides there with her family.
