Page 68 - RoadCem Manual - PCT BV

Colors should be recorded in a specific fashion. Soil should be moist. Although this is the most common way soil colors are recorded they can be recorded in the dry state. At all time the moisture status of the sample should be noted. Always use a freshly exposed face or ped and record what is being colored. Do not crush or rub the soil before getting a color unless it is an organic sample. Colors must always be determined in natural light (direct sunlight). Furthermore, colors should not be determined late or early in the day as the sun angle can alter the observed color. Colors should never be determined under artificial light. Finally, color should not be determined when one is wearing sunglasses or tinted glasses.
In describing colors it is important to determine the variation in color throughout the soil. Matrix color is the color that occupies the greatest volume. Some soils have several colors through the profile, the color that appears the most is recorded first and so forth.
Contrast refers to how easy it is to see a feature as compared to the matrix. There are 3 classes of contrast; faint, distinct, and prominent. Faint contrast is evident only on close examination. Distinct contrast is readily seen but moderate to the color to which compared. Prominent contrast is strongly contrasting colors to which they are compared (Table 4.2).
Table 4.2 Contrast chart.
Contrast Class
Code
Difference in color between Matrix and Mottle
Faint F
Distinct D
Prominent P
Hue
same same
same 1 page same 1 page
2+ page
Value
0 to <2 >2 to <4
<4 <2 >4 >2
>0
or
Chroma
and <1 and <4
and >1 to <4 and <1
or >4
or >1
or >0
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