Development of a soil test for determining the impact of soil disturbance

H Allen Torbert ,D L Gebhart

doi:10.31285/agro.16.672

Abstract

United States Federal law requires land-managing agencies like the US Army to identify and take into account the impacts of their undertakings on archaeological resources. Development of a method that uses changes in the stratification of horizon interfaces to identify the onset of adverse impacts to archaeological deposits was investigated. This method will allow Cultural resource managers to identify types and levels of military training that risk adverse impacts to intact archaeological deposits. A study was initiated at Fort Benning, GA, and Fort Riley, KS with treatments including (1) archaeological habitation/no-training, (2) archaeological habitation/training, (3) non-habitation/no-training, and (4) non-habitation/training. Soil core samples for each treatment group were taken for 0-10, 10-20, 20-30, 30-50 cm increments for chemical analysis. Several promising elements were identified that may be useful as indicators for determining potential damage to archaeological deposits resulting from ground disturbing activities such as mechanized maneuver training. Differences between disturbed and undisturbed treatment groups were often evident at depths of 20-40 cm, indicating substantial soil inversion, displacement, or mixing. Soil C concentrations were always negatively impacted in disturbed treatment group soils, indicating that C might also be a reliable indicator of disturbance, especially when used in a ratio with another elements that accumulate in undisturbed surface soil horizons. Analyses of ratios, including the Top-to-Total (ratio of upper 10 cm to entire 50 cm profile), the Total-to-Soluble (ratio of total elemental to soluble elemental concentration), and the Leachable to Non-Leachable (ratio of leachable/mobile element to a nonleachable/ immobile element) indicated promising results.

Highlights

Archaeological sites consist of artifacts and features that occur in soil and/or sediment matrices
The technical objectives of this research were 1) to demonstrate that naturally occurring and culturally induced stratigraphic differences in a suite of soil parameters such as SOC and chemical elements (e.g. P, Mg, Ca, Zn, Cu, Pb) at the interface of near-surface soil horizons can be disrupted to varying degrees by military training and other human actions and 2) to use this predictable stratification as the basis for an innovative, low-cost, widely applicable, reliable method to identify the onset and quantify the extent of adverse impacts to archaeological deposits that are associated with military training
Soil C, pH, calcium, magnesium, manganese, nickel, and phosphorus values were different for disturbed treatment groups to depths ranging from 10 to 30 cm when compared to undisturbed treatment groups, suggesting these variables may have utility in estimating severity and depth of disturbance

Summary

Introduction

Archaeological sites consist of artifacts and features (constructed facilities such as houses, hearths, and storage pits) that occur in soil and/or sediment matrices. A site’s scientific and cultural value and eligibility for the National Register of Historic Places (NRHP) is closely related to its depositional integrity which is the degree to which the three-dimensional relationships between artifacts, features, soils and sediments are similar to those that existed when the site was formed. Modern human activities (e.g., agriculture, infrastructure development, and military training) and natural processes can alter or destroy the spatial relationships and associations among artifacts and features, thereby reducing the site’s integrity (1 and 2). Archaeological deposits that occur at or very near the current ground surface have, in many cases, already been adversely impacted by historic or recent plowing, military training, infrastructure development and maintenance, or other actions.

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Conclusion