ABSTRACT
Compared with research on mineral soils, the study of the physical properties of organic soils in the United States is relatively new. Always (1920) and Anderson et al. (1951) considered the value and reclamation of peats in Minnesota and nationally. Davis and Lucas (1959) summarized organic soil formation, utilization, and management in Michigan; however, most of the literature on the detailed physical properties of peat was published from 1956 to 2003. This is true in Europe as well (Parent and Ilnicki 2003), except for a study by von Post (1922) who developed a eld method for determining
CONTENTS
Introduction ......................................................................................................... 135 Expression of Water Content and Bulk Density ............................................. 140 Correlation of Ash Content and Bulk Density ................................................ 141 Correlation of Bulk Density and von Post Degree of Humication ............ 142 Available Water-Storage Capacity in Organic Soils ....................................... 143 Water Retention in Organic Soils ...................................................................... 145 Fiber Content and Bulk Density in the Lake States ........................................ 148 Fiber Content and Degree of Decomposition: An International Review .... 151 Hydraulic Conductivity ..................................................................................... 154
Early Work at the MEF: A Tabular Association with Drainable Porosity ............................................................................................................ 154 Hydraulic Conductivity and Fiber Content Correlations ........................ 154 Hydraulic Gradient and Groundwater Velocity ........................................ 157 Hydraulic Conductivity and Degree of Humication .............................. 157
Summary of Physical Properties of Organic Soil............................................ 160 Evaluation of Wetland Drainage ....................................................................... 164 Impact of Wetland Drainage .............................................................................. 171 Conclusions .......................................................................................................... 172 References ............................................................................................................. 173
the degree of humication (decomposition) that is used widely outside of the United States (Box 5.1). A comprehensive series of studies on peat physical properties were conducted by Don Boelter (1959-1975), rst at the Marcell Experimental Forest (MEF) and later throughout the northern Lakes States to investigate how to express bulk density (Db, weight or volume basis), water retention characteristics, hydraulic conductivity (K), ber content, specic yield (drainable porosity), and the degree of decomposition (pyrophosphate test). Juhani Päivänen, a graduate student from the University of Helskinki, spent nearly a year at the MEF to learn the techniques developed there. Upon returning to Finland, he sampled extensively in central Finland and developed a physical-property data set similar to that of Boelter. Together, the data of Boelter and Päivänen represent one of the largest examinations of the physical properties of peat. After 1975, physical-property studies continued at MEF including a detailed examination of ber contents in Lake State organic soils, a comparison of international methods for physical properties,
BOX 5.1 VON POST FIELD-TEST PROCEDURE FOR H VALUE
Take samples about 5 m from prospective well sites. A Russian peat corer (Macaulay) or bucket auger may be used. Each horizon with a different H value should be evaluated. Take samples to at least 1.3 m or until a mineral-soil contact is found. Part of each sample can be retained for verication but the H value should be determined immediately using saturated soil or with water added if the soil is dry. Place enough soil to ll the hand when the ngers are gently curved against the palm. Gently bounce this egg-shaped soil until it just ts your hand. Add or remove soil to ll the gently curved pocket in your hand. Squeeze the sample as hard as you can. In the other hand catch the amorphous material and water squeezed between the ngers. Note the color and turbidity of the free water (water that is separate from any amorphous material). Thinning the water by opening the second hand facilitates the examination of color and turbidity.
