COLOR AS A CRITERION FOR THE RECOGNITION OF PODZOLIC B HORIZONS

Three hundred and fifty-three B horizons from acidic, well- to imperfectly drained soils from northern Ontario were sampled in an effort to test and possibly refine the current color and pyrophosphate-extractable Fe and Al criteria as presently used in the Canadian System of Soil Classification. Each of the soils sampled displayed podzolic morphology in the form of reddish brown to brown B horizons that became yellower and/or paler with depth and underlay LFH and Ae horizons. The soils belonged to the Podzolic (171 sites) and Brunisolic (182 sites) Orders. It was found that as the hues became redder and the values darker there were increases in the means of pyrophosphate-extractable Fe (Fe p ), and Al (Al p ) and of C (C p ). Soils with sand textures (sands and loamy sands) required less Fe p plus Al p to give the same colors as finer textured soils. Using two schemes for attributing color codes to the Munsell Colour Chips, C p was found to be the soil property most highly correlated with soil color. By revising the current color and Fe p and Al p criteria it was found that the soils could be correctly classified using color 78% of the time, compared with only 52% using the present criteria. Key words: Soil color, soil classification, pyrophosphate-extractable Fe, Al, C