Canfield Silt Loam, a Fragiudalf: II. Micromorphology, Physical, and Chemical Properties

Abstract

AbstractAlthough cutans comprise less than 1 to 2% of the total soil volume, they impart a disproportionately large influence to the soil as a medium for plant growth. This impact is maximized in the Canfield fragipan where rooting volumes are almost exclusively restricted to polygonal ped interfaces. Sampling these morphological units of fragipan horizons revealed twice as much total clay and three times as much < 0.2µ clay in the cutan segments of the horizon as in the matrix material or bulk horizon sample. Quantities of exchangeable cations were roughly proportional to the clay content, but the exchangeable K and Sr were nearly four and five times more concentrated, respectively, in the cutanic material, suggesting a possible mineralogical difference between the cutan and matrix or bulk mineralogy. X‐ray analysis indicated that the total clay fraction of the cutan material contained a greater proportion of nonexpandable and expandable 14Å and 17Å minerals, as well as interstratified components, when compared to the matrix and bulk clay fraction. Thin section analysis in conjunction with textural analysis and profile descriptions verified the presence of an argillic horizon above the fragipan and revealed the laminar morphology of the polygonal interface. From these data and observations the genetic sequence of the Canfield series is suggested.