Genesis of Miami Silt Loam

Abstract

Abstract Miami silt loam and other Gray‐Brown Podzolic soils of the United States and Canada are developed from calcareous parent materials of glacial, glacial‐fluvial or loessial origin; a large proportion of these materials were deposited during the Wisconsin stage of glaciation. Study of thin sections with polarized light shows clearly that much of the clay of the B 2 horizon has been carried in by water and deposited. Studies of the clay fraction of the soil and parent material indicate that much of the clay was either unaltered or has been transformed from clay originally present, but that some was formed by weathering of primary minerals. Characteristics of the A horizon may be ascribed to the joint effects of leaching, eluviation, and the influence of the broad‐leaved deciduous forest and the associated macro‐ and micro‐fauna. Recent leaching experiments, using “undisturbed” soil columns of Miami silt loam, suggest that B horizons are developed primarily through translocation of suspended fine clay and some humus, especially after the periods of soil drying in late summer and early autumn.