Color Diagnostics of Soil Horizons (by the Example of Soils from Moscow Region)

Abstract

Soil color is the most important diagnostic feature in soil studies, though still being determined mainly qualitatively. Uncertainty in color determination can be eliminated by the transition to the precise color estimate in the CIELAB space coordinates. The results of color study for 347 soil samples are presented. These samples were obtained from the area of 274 ha in the southern taiga landscapes. The possibility to differentiate between twelve main horizons according to their color characteristics in both wet and dry states is shown for ten soil types (podzolic, bog podzolic, lowmoor peat bog, soddy, soddy gley, acid soddy alluvial, acid meadow alluvial, meadow-bog alluvial, silty mucky gley alluvial, and silty-peat bog alluvial soils). The color characteristics of soil horizons correlate with the landscape positions of the soils: watershed slopes, terraces, ravines, backswamps, and floodplain of the Klyazma River. Among three optical indices (L*, a*, and b*), only lightness (L*) correlates reliably with the horizons distinguished in the Classification and Diagnostics of Soils of the Soviet Union (1977), Classification and Diagnostic System of Russian Soils (2004–2008), and the World Reference Base for Soil Resources (2014).