Fjölrit RALA - 15.06.2004, Side 105

linearly. A general trend to darker colors was observed with increasing OM content also with
the CIE parameter (Fig. ld). The scatter of the Munsell values and CIE data could be partly
correlated to the type of volcanic parent material, the texture and the chemical composition of
organic matter (Humic /Fulvic acid ratio etc.). Significant correlation was observed between
soil Fe (extracted by dithionite) and Munsell croma, indicating that the Fe bearing minerals
are especially important to color development in volcanic soils (Fig. lc). Soils with high
croma contained higher amounts of crystalline Fe oxides and had undergone more intense
weathering. Munsell hues of 7.5 YR and high chromas indicate that goethite and hematite
were important products of weathering. Many B horizons are lighter. Among B horizons,
there are strong differences according to the position in the landscape (redoximorphic
features, kind of piroclastic deposit, etc.). These preliminarily results suggest that there was a
close relationship between the Munsell parameters, organic matter content and type of iron
oxides for volcanic soils; this occurs especially for the soil profiles in the same landscape.
Relationship between In sltu and laboratory measurement of Munsell
value
a
S 7
E 5
2 A
> 8
— <B
®
E
= S 3
8
1
• ••• •
>••••••
• • I
• •• •
• •
• •
••
5 5 5,5 6 6,5 7 7,5
Mun9ell value Laboratory measurement
Munsell Chroma vs Fe Dithionite
Munsell Value vs Organic Matter
CIE Parameters X-Y-Z (tristimulus) vs Organlc Matter
(Spectrophotometer Measurement)
$X (Tristimulus) (Tristimulus)
(Tristimulus)
0,00 5,00 10,00 15,00 20,00 25,00 30,00 35,00 40,00
Organic Matter (%)
References
Baumgardner, M.F., Silva, L.R., Biehl, L.L., Stoner, E.R., 1985. Reflectance properties of
soils. Adv. Agron. 38, 1 -44.
Soil Survey Staff, 1999. Soil taxonomy: a basic system of soil classification for making and
interpreting soil surveys, 2nd edition. Agriculture Handbook, vol. 435. USDA, US
Govemment Printing Office, Washington DC.
Stoner, E.R., Baumgardner, M.F., 1981. Characteristic variations in reflectance of surface
soils. Soil Sci. Soc. Am. J. 45, 1161- 1165.
Torrent, J., Barron, V., 1993. Laboratory measurement of soil color: theory and practice. In:
Bigham, J.M., Ciolkosz, E.J. (Eds.), Soil Color. SSSA, Madison, WI, pp. 21-34.
Torrent, J., Schwertmann, U., Fechter, H., Alferez, F., 1983. Quantitative relationships
between soil color and hematite content. Soil Sci. 136, 354— 358.
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