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The Munsell color code system is the system which describes all colors,
not just soil colors but all colors.
There are three components to the Munsell color code system.
It consists of the hue, which is the color of the rainbow, the value,
the lightness or darkness of the chip and the chroma, which actually
imparts an intensity to the color of the chip that you're actually seeing.
So let's determine soil color.
It's a lot easier for soil to be in a wet situation.
You can wet up the soil very easily than it is to wait for the soil to dry.
So, soil color is usually taken moist.
This is the Munsell color code book and
I'm turned to the 10 YR hue page which is actually very common for the soils here.
So, you're taking the moist soil and you're putting it in the back of
the chart, and you're trying to match it up with one of the colors.
And it just so happens that this particular soil
has a color matches up quite closely with 10YR hue value of 3 and
a chroma of 4, for a color of 10YR3/4.
And then you can flip to the side over here,
you can look at the side, it's dark yellowish brown.
The two principal components that give soil its color are iron and
organic matter.
And on display right here, what you can see are all the different
colors that result from different oxidation states of iron.
So for example, you have this deep maroon color, you have
this brown color, you have the yellowish color, you have these tan colors.
This is one of the major coloring components of soil is iron.
The oxidized iron, Fe plus 3
imparts lots of reds,
browns, yellows, tans, oranges and so forth.
The absence of iron imparts a very grey color to the soil.
Reduced iron is an iron which is in the form of Fe plus 2,
for example, is very mobile in the soil and so it sorta leeches out of the soil,
and what you are left with, are these grey colored soil particles.
So what you probably notice looking at a soil, is that soils
have mixtures of colors, and when we have mixtures of colors we call that mottling.
So, the second principal component of soil that imparts color
is organic matter.
So we have an example of a Maumee Sandy Loam here and
what we've done is actually we've combusted that soil, all right?
In this sample over here and
as you can see the organic matter really imparts a dark color to the soil.
Whereas over here in that sample where the organic matter is removed,
it's very light in appearance.
So also you find soils that are very dark in appearance on the surface.
This is a soil from Iowa.
Lots of organic matter imparts are very dark color,
compared to soils from Alabama, Georgia, Tennessee, Mississippi
that are very red in appearance have a very low organic matter content.
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