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A COMPARISON OF MOLLISOLS FROM THREE DIFFERENT CLIMATIC REGIONS IN THE UNITED STATES (NEBRASKA, NEVADA, OREGON)
Abstract
Soils in the Mollisol Order are recognized by their high base saturation, and by high organic matter content with an attendant dark color in the upper pedon. The intent of separating these soils from others was to designate a group of soils unique in properties that were the result of soil forming environments in the semiarid to subhumid prairie. However, it appears that soils with properties that presently placed them in the Mollisol Order exist in soil forming environments outside of the prairie concept. The intent of this study was to examine soils in these contrasting environments, to compare them with modal Mollisols, and to judge whether or not requirements of the Mollisol Order may be readjusted to retain the prairie concept associated with Mollisols. Ustolls formed in loess on broad drainage divides in central Nebraska were used as modal soils with which to compare soils in contrasting environments on mountains in Nevada and in pluvial lake beds in Oregon. In spite of differences in soil forming environments, presently used criteria for Mollisols were met by all soils sampled. Discriminant and cluster analyses, nested analysis of variance, and correlation procedures were used to test degrees of similarity among soils studied. These data suggested that the soils from the Nebraska and Oregon sites were much closer in soil properties than they were to soils at the Nevada sites. Data from discriminant analysis, cluster analysis and nested analysis of variance procedures may be used to determine the magnitude of differences that are tolerable in the Mollisol Order. Using such data, limits can be developed that will assist in setting ranges at the different levels. It was suggested that properties so easily modified by cultivation are less useful to differentiate soils of the highest level of the taxonomic system than are those that remain in the soil even after a long term of cultivation. Also, it was proposed that a criterion of organic matter C:N ratio, of less than or equal to 12:1, of organic matter in the epipedon be added to criteria presently established for the mollic epipedon, and restrict the mollic epipedon particle size class to those finer than coarse loamy, except for coarse silty.
Subject Area
Agronomy
Recommended Citation
MAYS, MAJOR DEWAYNE, "A COMPARISON OF MOLLISOLS FROM THREE DIFFERENT CLIMATIC REGIONS IN THE UNITED STATES (NEBRASKA, NEVADA, OREGON)" (1982). ETD collection for University of Nebraska-Lincoln. AAI8302106.
https://digitalcommons.unl.edu/dissertations/AAI8302106