Date of Award
Master of Science (MS)
Plant and Environmental Science
Determining soil color has traditionally been done visually, but inaccuracies with this method have been documented, including disagreement in evaluators, to differences in physical color books. Determining Munsell soil color in the field is also subject to environmental conditions, including soil water content (SWC) and light intensity. New digital spectral technology designed for determining soil color may offer accurate assessments regardless of human inaccuracies and environmental conditions. This research aimed to assess if visual observations differed from digital measurements of Munsell soil color as well as, the impacts of SWC and light on visual observations and digital measurements of soil color value and chroma, the two color components most important for soil use interpretations for siting and designing onsite wastewater systems. Munsell color was measured using the XRite Capsure and visually using Munsell Color Books on 111 soil horizons from three South Carolina regions. Distance between hues were similar among assessment methods although visual observations of value and chroma were significantly greater than digital measurements. Regardless, color values and chromas were less than one chip difference suggesting no practical difference in the two methods. While in general higher color values and lower chromas were determined from oven dried peds in comparison to field moist peds, the influence of SWC was region specific. Of most importance were higher color chromas documented from field moist peds compared to oven dried peds in the Coastal region. In this region gley chromas were determined in unsaturated soils emphasizing the importance to carefully evaluate other landscape features when interpreting the soil for onsite wastewater treatment. While SWC affected the agreement between digital measurements and visual observations, in most regions the difference was less than one color chip and of no practical significance. Varying PAR did not affect digital measurements and had minimal influence on visual observations. Digital measurements of soil color value and chroma may offer validation of soil color under varying lighting conditions and could be a promising tool for training new soil evaluators in color assessment.
Hill, Isabella, "Soil Moisture and Light Conditions Impact Digital and Visual Soil Color Assessments" (2021). All Theses. 3673.
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