Soil Color

1
Soil Color Its Causes
2
Factors that give soil color

1. Organic matter
2. Weathered mineral material composing the soil
3. Quantity and condition of iron present

3
Dark Color in the A Horizon

• Usually indicates the presence of organic matter
• This is a characteristic of the A horizon

4
Sub-soil Color Determination

• Quantity and condition of iron
• Red colors usually associated with unhydrated
  iron oxides and indicate a well drained soil
• Yellow colors largely due to hydrated iron
  oxides and generally indicate a somewhat more
  moist condition than red colors

5
Basic Color Classifications

• Light
• Medium
• Dark

6
Color Determination in the field

• ALWAYS USE MOIST SOIL
• Munsells color charts
• Absolute black 0
• Absolute white 10
• Light soils hue value 7 or more
• Medium soils hue value 5 6
• Dark soils hue value 4 or less

7
Munsell Color Charts

• Hue dominant spectral or rainbow color
• Red, Yellow, Blue, Green
• Value relative blackness or whiteness
• Reflected light
• Chroma purity of color
• Number increases and the color is more brilliant
  as grayness decreases

8
Change in soil color

• Indicates a difference in the soils mineral
  origin (parent material)
• Or change in soil development

9
Mottles

• Spots of different colors in the soil
• Generally indicate that the soil has periods of
  inadequate aeration each year
• Usually rust colored
• Bluish, grayish, greenish subsoils (gleying)
  with or w/o mottles indicate longer periods
  each year of waterlogged conditions inadequate
  aeration.