Worm‐Worked Soils of Eastern South Dakota, Their Morphology and Classification

Abstract

AbstractSoil survey field mapping of Brookings County, South Dakota, showed extensive areas of soils with nearly complete destruction of zonal profile horizonation as the result of mixing by intensive worm‐working. These worm‐worked profiles have moderately thick, black, recognizable A1 horizons, grading through completely mixed horizons of B2 with A1, A1 with B2, B3ca with B2, B2 with B3ca, or other combinations of horizons, before grading into the comparatively unmixed parent material. Laboratory analyses were made on some of these profiles in conjunction with the survey and with this study. Field studies were later extended, through the use of transects, to the surrounding areas of South Dakota. From these transect studies the area of occurrence of these soils was delineated. Worm‐worked soils were found in Wisconsin tills ranging from Iowan through Mankato in age and also in Wisconsin loess mantling the Iowan and Tazewell tills. These profiles resemble in some characteristics the “thick” or “fat” Chernozem of Europe. The name “Vermisol” is suggested to represent a more specific group classification for grassland soils displaying the unique profile characteristics associated with intensive worm‐working.