Preliminary Study of the Morphology, Genesis and Classification of Some Soils Developed from Pierre Shale

Soil scientists have recognized that there are differences in crop adaptability and yields of crops and range grasses among the well-drained clay soils developed from Pierre shale in the Chestnut region of western South Dakota. It is difficult, however, to measure quantitative differences in soil characteristics among these soils which are unlike agronomically. As a result the Pierre soil series which includes well-drained clay soils developed from clay residuum over bedded shale is mapped over the entire area. The reason that these fine textured soils appear similar is that the dark olive-hued shale and shale residuum tends to mask out any striking color, structure and consistence differences in soils across the climatic continuum of their occurrence. The purpose of this study is to compare soil profiles taken from well-drained sites representing the climatic range of this continuum to see what soil differences, even though small, might be apparent to a field morphologist, and also to ascertain what differences can be detected in soil characteristics determined in the laboratory. Using these comparisons, Pierre soil series criteria will be examined to see if the present range of the series is too broad