CCZO -- Soil Texture -- Argillic Horizon -- Calhoun CZO -- (2016-2017)

Historic agricultural practices throughout the Piedmont region of the southeastern United States from ~1820 to 1940 led to accelerated erosion. Practices, such as tilling, degraded soil quality altering hydrologic processes on the landscape by limiting infiltration and leading to overland flow and erosion. Erosion due to these practices has substantially redistributed sediment from upper to lower landscape positions, causing a change in the depth-to-argillic horizon along hillslopes. By mapping the depth to argillic horizon within watersheds that have a history of farming and watersheds with little evidence of agricultural disturbance, a better understanding of the effects of farming practices on erosion and sediment redistribution can be made. This study uses extensive soil sampling within historically farmed and unfarmed watersheds to map spatial variations in the depth to argillic horizon. In addition to sampling, Electro-magnetic Induction (EMI) is being tested and calibrated to clay content and other topographic characteristic (i.e. landscape position, aspect, percent slope) from which the depth to argillic horizon can be predicted. Current hillslope and watershed hydrologic models use characteristics from soil classification maps for parameterization, however, these soil maps may lack sufficient spatial detail and may not accurately represent landscapes that have been eroded from historical farming. The results from this study will improve understanding of previous erosion on sediment redistribution and will characterize the potential use of electromagnetic induction as an accurate and efficient means to predict the depth to the argillic horizon. This information will improve parameterization of hillslope and watershed hydrologic models.

自1820年至1940年，美国东南部皮德蒙特地区的农业历史实践导致了土壤侵蚀的加速。诸如耕作等农业实践，通过限制渗透并导致地表径流和侵蚀，降低了土壤质量，并改变了地表的水文过程。这些实践导致的侵蚀显著改变了从上游到下游的景观位置之间的沉积物分布，进而改变了坡面上的粘土层深度。通过对具有农业历史和农业干扰证据甚少的流域内粘土层深度的测绘，可以更好地理解农业实践对侵蚀和沉积物再分配的影响。本研究通过在历史耕作和非耕作流域内进行广泛的土壤采样，以绘制粘土层深度的空间变化图。除了采样外，还在测试和校准电磁感应（EMI）技术，以预测粘土层深度，该技术基于粘土含量和其他地形特征（例如景观位置、朝向、坡度百分比）。当前的山坡和水文模型使用土壤分类图的特征进行参数化，然而，这些土壤图可能缺乏足够的空间细节，并且可能无法准确代表历史上由于农业活动而遭受侵蚀的景观。本研究的成果将增进对先前侵蚀和沉积物再分配的理解，并将电磁感应作为预测粘土层深度的准确和高效手段的潜在用途进行表征。这些信息将改善山坡和水文模型的参数化。