What gives soil its color what does the color of soil tell you?

Answer 1

soil color comes from a multitude of things. most likely, the chemical composition depending on where in the country you are located. soils in the southeast (ultisols) tend to be high in red hues (10YR, 5R). This is from the iron in the soil. Soils in the northeast are high in organic matter, and tend to be more brownish black. Soils in the desert southwest tend to be more neutral brown, from eolian sands (mixed or siliceous), soils in the Midwest tend to be almost blackish due to farming and high organic matter deposted by the Mississippi, and soils in salty areas tend to be white (calcium sulfate, calcium carbonate). Although this is more of a blanket statement, because soils can vary from one side of your yard to the other. Most colors are derived from the type of bedrock that is underlain, or the type of bedrock upslope/upstream from where the soil was deposited. Although no physical properties can be determined from soil color (other than high water table by evidence of redoximorphic features), soil color is used by USDA to as a series criteria in the range of characteristics, in order to help farmers or users identify soils. By the way, redoximorphic features will be colored reds and greys, and is from the direct reduction and oxidation of iron in the soil. One other note, soils can be gleyed (greenish grey), which will be from just reduction occurring (this is found in wetland or saturated conditions) and is generally associated with a sulfur like smell.