Characteristics and Classification of Three Wisconsin Histosols

Abstract

AbstractOn the basis of morphology, pH, and solubility in Na4P2O7, three Wisconsin histosols were classified as (i) a Fibrist, (ii) a Hemist, and (iii) a Saprist.Fiber content was found to be the single most useful characteristic in the classification of these Histosols, and in quantifying various stages of decomposition and soil formation in histic materials. Fibric material consisted of 70% or more fiber as determined on a gravimetric basis, using a 140 mesh sieve to separate fibrous (> 0.1 mm) from nonfibrous (< 0.1 mm) material. The fiber content of hemic material ranged from 35 to 60%; sapric material contained < 15% fiber. Sodium pyrophosphate extract color (SPEC) is a useful parameter in the characterization and classification of histic materials.Results of other analysis showed that the carbon content of the organic fraction was highest in the Saprist and lowest in the Fibrist. Oxygen and hydrogen contents were, in general, inversely related to fiber content. Total nitrogen appeared to be dependent on botanical composition of parent plants and microbial activity of the soil; the relatively high nitrogen content of certain subsurface layers may be related to illuvial deposition of mobile, nitrogen‐containing substances. Mineral content was likely influenced by additional colluvial or eolian sediments.Good structure was found in both surface and subsurface layers of the Saprist. It is suggested that highly decomposed Saprists possessing good structure in surface and subsoil horizons be placed in a separate great group.