Masters Theses

Date of Award

12-2005

Degree Type

Thesis

Degree Name

Master of Science

Major

Environmental and Soil Sciences

Major Professor

Neal Eash

Committee Members

Sarah Sherwood, John T. Ammons

Abstract

ABSTRACT

Part I

The Red River Valley of Eastern Kentucky contains cultural remains that point to the independent development of agriculture during the Late Archaic cultural period. The objective of this study is to gather quantitative data through the chemical and physical analysis of soils collected within a valley transect to gain insights into landscape processes and soil quality that may have played a role in the development of plant domestication. National Cooperative Soil Survey standards were used for field descriptions and the chemical and physical analysis of all samples. Soil quality values such as ECEC (ammonium acetate pH 7), pH (1:1 soil, water), Available P (Bicarbonate), Organic C and N (dry combustion C analyzer), and particle-size (pipette method) are plotted versus landscape position to determine what slope position contains soils suitable for hillside food plots. Relative soil age indicators such as extractible iron (citratedithionite method), B horizon thickness, and clay accumulation are used to interpret landscape processes and relative age of the numerous slope failures in the region. Upland soils had the highest ECEC and base saturation compared to other landscape positions. Outcrops of Mississippian carbonate bedrock are contributing basic cations to upland soils resulting in high base saturation. Soil morphology indicates that the landslides encountered within the transect are late-Holocene in age. These slides were likely generated by mid to late-Holocene climatic shifts in which the frequency and intensity of summer precipitation increased across the southeastern United States. These landslides may have contributed to the development of plant domestication by providing disturbed soils in which weedy plants (such as those domesticated by indigenous people) thrive.

ABSTRACT

Part 2

The Western Cumberland Escarpment in Eastern Kentucky has slopes developed in sedimentary bedrock of Mississippian and Pennsylvanian age. This study was conducted in order todetermine the affects of slope position, aspect, and changes in bedrock on soils developed in these lithology segmented slopes. Chemical and physical soil characteristics such as ECEC, base saturation, pH, soluble cations, organic C, particle size, and free iron are plotted versus slope position in order to determine the relationship between pedologic and geomorphic processes and slope position in this landscape. Correlation coefficients are then calculated and trend lines plotted in order to determine if a correlation exists. The soils of the SW facing slope had a moderate to strong statistical fit (r2>0.60) for solum depth, extractable Fe, base saturation, soluble cations, organic C, sand content in the A horizon, and Profile Darkness Index (POI). Poor correlations existed for clay ratios and pH. Soils of the NE facing slope had a moderate statistical fit (r2>0.60) for solum depth, extractable Fe, base saturation, soluble cations, fine silt content in the A horizon, ECEC, and POI. Poor correlations existed for pH, sand content of the A horizon and organic C. Carbon accumulation index indicated that carbon is being retained at the summit of the SW facing slope and is accumulating at the base of NE facing slope. The influence of changes in bedrock lithology is apparent in the base status of upland soils as outcrops of carbonate bedrock contribute basic cations. The NE facing slope had thinner sola, less extractable Fe, lower clay ratios, lower base saturation, and lower pH than the soils of the SW slope. Increased moisture contents on the NE facing slope may have contributed to the landslides found in the lower slope positions.

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