Does 20 Years of Tillage and N Fertilization Influence Properties of a Claypan Soil in the Eastern Great Plains?

Core Ideas Claypan soil properties were minimally affected by tillage and N fertilization after 20 years. Soil organic matter distribution was affected by tillage, but with no apparent net difference. Long‐term tillage and N fertilization did not affect soil bulk density or penetration resistance. Subtle long‐term soil changes may not influence producer choices for tillage and N fertilization. Tillage and nitrogen (N) fertilization systems may affect soil chemical and physical properties, especially long term. This study's objective was to examine the effect of three tillage systems (conventional tillage, reduced tillage, and no‐till) with four N fertilizer treatments on properties of a claypan soil in the eastern Great Plains after 20 yr of cropping. Soil chemical and physical properties were little affected by long‐term tillage and N fertilization. The lack of tillage to distribute soil phosphorus (P) and potassium (K) nutrients within no‐till treatments resulted in lower P and K values below the surface. In no‐till, the accumulation of organic matter in the surface soil (0 to 7.5 cm) was countered by lower organic matter in the 7.5‐ to 15 ‐cm zone, resulting in no net increase compared with the other two tillage systems. Soil bulk density and penetration resistance in the surface 30 cm were unaffected by tillage or N fertilization.