Physical Properties of Peats as Related to Degree of Decomposition

TLDR

Peat physical properties such as water retention, yield coefficient, and hydraulic conductivity vary widely in northern Minnesota peat, largely because degree of decomposition controls porosity and pore size, with fiber content (>0.1 mm) and bulk density used to distinguish fibric, hemic, and sapric types. Regression analyses showed that water content at various suctions correlates curvilinearly with fiber content and bulk density (R² .66–.88), while hydraulic conductivity relates linearly (r² .54), demonstrating that classifying peat by degree of decomposition using these metrics provides substantial insight into its physical characteristics.

Abstract

Abstract Important physical characteristics, such as water retention, water yield coefficient, and hydraulic conductivity, vary greatly for representative northern Minnesota peat materials. The differences are related to the degree of decomposition, which largely determines the porosity and pore size distribution. Fiber content (> 0.1 mm) and bulk density are properties often measured to indicate the degree of decomposition of peat materials and are criteria used to distinguish fibric, hemic, and sapric peat types. Regression analyses showed a curvilinear relationship of water contents at saturation, 5 mbar, 0.1 bar, and 15 bar suctions, to fiber content (> 0.1 mm) and bulk density with coefficients of multiple determination ( R 2 ) ranging from .66 to .88. Regression analyses of the logarithm of hydraulic conductivity on fiber content (> 0.1 mm) and bulk density indicate a linear relationship ( r 2 = .54), although not as great due to the variability of hydraulic conductivity. Thus the classification of peat materials and organic soils based primarily on degree of decomposition as measured by fiber content and bulk density would relate significant information about their physical characteristics.