Fragipan Soils Research Articles

Tile Drainage of a Sloping Fragipan Soil

Tile Drainage of a Sloping Fragipan Soil

Fragipan Soils: Certain Genetic Implications

AbstractThis study of a number of fragipan soils derived from a wide range of parent materials was undertaken to test an hypothesis concerning fragipan formation which had as its foundation data obtained from loessial soils. Particle size distributions and selected chemical properties were determined and comparisons of the data for the Bx and adjacent horizons were made. The portion of the original hypothesis suggesting that fragipan soils were severely leached prior to pan formation and that pan formation resulted from tight packing of dispersed clay particles is acceptable with certain limitations. On the other hand, it cannot be accepted that Ca:Mg or Ca:Mg + Na ratios are factors of general importance in fragipan formation.

Fragipan Soils of Illinois: II. Mineralogy in Reference to Parent Material Uniformity of Hosmer Silt Loam

AbstractThe mineralogy of Hosmer silt loam, a bisequal soil with a fragipan, was investigated in order to determine whether there is a lithological discontinuity between the parent material of the upper and lower sequum.Differences observed between the two sequa in respect to the mineralogy of the heavy and light, silt‐size fractions may be accounted for by a progressive decrease in the weathering intensity with depth and are not suggestive of a lithological discontinuity in parent material. The clay mineralogy for the B horizons of the two sequa was similar for the < 0.2µ and the 0.2µ to 2.0µ fractions, taken individually. However, for the total clay fraction, a higher percent of montmorillonite was found in the B′2 horizon of the lower sequum; this may be explained on the basis of illuviation.

Fragipan Soils of Illinois: I. General Characterization and Field Relationships of Hosmer Silt Loam

AbstractBisequal soils with fragipans are common in southern Illinois. The purpose of this introductory paper is to set the general framework for understanding the nature and occurrence of these soils through the description of the morphology, chemical and physical properties, and field relationships of Hosmer silt loam, a soil with moderate fragipan expression.The bisequal nature and expression of the fragipan increase with decreasing loess thickness and with latitude from north to south. Maximal expression is in the low, moderately well‐drained, topographic positions. It is suggested that these soils in Illinois are part of an interstate sequence extending southward into Mississippi, within the loess‐derived soils of the Mississippi River Valley.