Vertisols and Vertic Properties of Soils of the Cherokee Prairies of Kansas

Abstract

Soils in the Kansas Cherokee Prairies have formed in various parent materials and exhibit differences in the degree of expression of vertic properties. Despite large clay contents, few soils meet the criteria for a Vertisol. In an effort to investigate the cause of these differences, pedogenic processes, primarily clay illuviation and shrink–swell processes, were evaluated in eight pedons. Relatively high coefficient of linear extensibility (COLE) values were found in all soils. The clay mineralogy of four sites was dominated by smectite, but only two of those sites classified as Vertisols. In the other four sites, smectite was the most common clay mineral, yet there were several other clay minerals present in significant quantities. Disruption of illuvial clay features by shrink–swell movement was evident in the thin sections of all soils. Striated b-fabrics dominated except in surface soils that exhibited a small COLE value and occurred above an argillic horizon. Linear planes lined with stress-oriented clay and representing zones of shear failure were observed, along with argillans that had been distorted and embedded within the matrix by swelling pressure and soil movement. In conclusion, when present, a nonexpansive silty surface layer acts as a buffer and may limit shrink–swell by allowing expansive subsoils to dry more slowly.