Some morphological and chemical aspects of peats applied to the characterization of histosols

Five peats—Mesic Humisol (Hemic Medisaprist), a Fibric Mesisol (Fibric Medihemist), a Typic Mesisol (Typic Medihemist), and two Humic Mesisols (Sapric Medihemists)—were selected to include differences in landform, botanical composition and degree of decomposition. Special attention was devoted to the nonhumic fraction, especially the particle-size fractions. The peats and peat fractions were characterized according to their chemical and morphological features, to gain information useful in peat differentiation and interpretation.The proportions of fine materials and voids were the main micromorphological peat features. They varied inversely, indicating a decrease in porosity as peat materials become more decomposed. The particle-size fractions, especially the 150− to 500-micrometer fraction, were the source of indicator plant macrofossils that can be used to determine peat-forming plants and type of peat materials. These indicator macrofossils, along with the micromorphological elements, are of special assistance in differentiating the more decomposed peat.The results indicate that the evaluation of the peats through the various parameters was in line with that obtained by the rubbed fiber content and the P2O7 index, two conventional and widely accepted criteria for peat characterization. However, the additional information gained through the micromorphological measurements, determinations on size fractions, and examination of macrofossils could be used efficiently in differentiating poorly characterized peat soils (Mesisols) and in determining the behavior of peats under cultivation.We concluded that micromorphological measurements, particle-size distribution, and macrofossil analysis of size fractions can be used in support of commonly used criteria for differentiating peats; in addition, they provide an essential basis for peat interpretation.