Hydraulic Conductivity and Pedogenesis of a Benchmark Loess Catena in Southern Indiana.

Benchmark soil landscape studies are crucial for understanding the relationship of soil properties to hydropedologic processes. The objective of this research was to characterize soil hydraulic properties related to pedogenic features in loess over residuum soils. The study site was characterized as soils developed in loess over residuum from sandstone and shale on bedrock controlled landscapes. Soils were sampled at key landscape positions (summit, shoulder, middle backslope, lower backslope, and footslope) of a small pasture watershed. Full soil characterization was conducted by the NSSL in Lincoln including geochemical trace element analysis. In addition to laboratory analysis, constant head permeameter (Ammozemeter) tests for in-situ hydraulic conductivity were conducted. The results of this study indicated that Ap horizons for all landscape positions had very similar Ksat values (0.3-0.7 cm/hr). Summit position had consistent Ksat values throughout the profile (even in the fragipan) and ranged from (0.44-0.60 cm/hr) which may be due the loess parent material which occurred in all horizons analyzed. Additionally most of the loess horizons were notably uniform (0.3-0.6 cm/hr). With exception of the summit position, most fragipans/fragic horizons had substantially lower Ksat values compared to overlying horizons and  5 of the 7 fragic horizons were 1 order of magitude lower (0.02-0.05 cm/hr). Summit position Ksat patterns suggest little anisotropic lateral flow; however, other positions (loess/silty colluvium over residuum), the Ksat patterns provide evidence of anisotropic lateral flow associated with an aquitard effect.