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Thursday, April 1, 2010

Soil's Color


Ground color is a combination of various color components of the soil. Directly related to soil color in proportion of the total mix of colors that reflected the soil surface. Land of color is largely determined by the specific surface area multiplied by the volumetric proportion of each of the soil. The more specific surface area causes more dominant to determine the color of the soil, so the color grain soil colloids (colloidal inorganic and organic colloids) having a specific surface area is very wide, so it affects the color of the soil. Color humus, iron oxide and iron hydroxide determining soil colors. Iron oxide red, brownish or yellow depending on the degree hidrasinya. Reduced iron turquoise. Mostly white quartz. White limestone, gray, and there are olive-green color at the time. Red-colored feldspar. Gray clay, white, even red, depending on the proportion of this iron coat type.
Soil Color by Munsell

Besides the color of the soil also found some rusty color (mottling) in the form of spots. A rusty color and the movement of the dissolution of some soil components, mainly iron and manganese, which occurs during the rainy season, which was then experiencing precipitation (deposition) and deposition (change positions) when the soil has dried. This was mainly triggered by the occurrence of: (a) reduction of iron and manganese to form the solution, and (b) oxidation that causes precipitation. Bright rusty little happening on the ground that low levels of iron and mangannya, whereas dark rusty formed when iron and manganese are experiencing precipitation. Rusty rusty-formed is not immediately change despite the drainage improvements.

According Hardjowigeno (1992) that the color of the soil functions as a pointer of the nature of the soil, because soil color is influenced by several factors inherent in the land. The cause of differences in surface color is generally influenced by differences in soil organic matter content. The higher the organic matter content, soil color became darker. While the bottom layer, which is generally low organic matter content, soil color is much influenced by the shape and the number of Fe compounds in the soil. In the area of bad berdrainase, ie in an area that is always under water, all the land is grayed out because the compounds contained in the conditions of reduction of Fe (Fe2 +). On land berdrainase well, that is land that was never immersed in water, contained in the oxidation state of Fe (Fe3 +) for example in the compound Fe2O3 (hematite), which is red, or Fe2O3. 3 H2O (limonite), which is yellow brown. While on the ground that is sometimes wet and sometimes dry, then in addition to gray (reduced area) got too rusty rickshaw pedicab-red or yellow, ie in places where air can enter, resulting in oxidation of iron in place these. The presence of quartz mineral soil may cause the color becomes lighter.

According Wirjodihardjo in Sutedjo and Kartasapoetra (2002) that the intensity of the color of the soil affected the following three factors: (1) types and amounts of minerals, (2) soil organic matter content, and (3) soil water content and level of hydratation. Land that contains minerals feldspar, kaolin, limestone, quartz can cause a white color on the ground. Type of feldspar minerals cause a variety of colors from white to red. Hematite can cause soil to red color to dark red. The higher the organic matter content, the soil became darker color (dark) and conversely the less soil organic matter content soil, the color will appear brighter. Soil with higher water content or more humid to wet soil causes a darker color (dark). While hydratation level associated with the position of groundwater level, which apparently leads to a reduction of color (gleisasi) is blue-gray color to gray-green.
In addition, Hanafiah (2005) revealed that the color of the soil are: (1) as an indicator of soil parent material for the Beru develops, (2) indicators of climate conditions for the land that has been developed further, and (3) indicators of soil fertility or productivity capacity land. Generally it is said that: the dark land means higher productivity, besides there are many exceptions, but in a sequence as follows: white, yellow, gray, red, brown-grayed, reddish-brown, brown, and black. This condition is an integration of influences: (1) organic matter content of their dark, the higher the organic matter content of the soil, the land will be increasingly dark color, (2) the intensity of leaching (washing of the horizon at the top to the bottom of the soil horizon) of nutrient ions in the soil, the more intensive leaching process causes the soil becomes more bright colors, like on the horizon eluviasi, and (3) high quartz content of the soil is lighter in color.

Ground color is determined by comparing the color of the ground with a standard color on the Munsell Soil Color Chart book. Standard color diagrams are arranged three variables, namely: (1) hue, (2) value, and (3) Chroma. Hue is the dominant colors of the spectrum according to wavelength. Value indicates a dark bright colors, according to the number reflected ray. Chroma indicates the purity or strength of the color spectrum. Chroma is also defined as the gradations of color purity or degree of differentiation of color changes from gray or white neutral (0) to another color (19).

Example

Hue is divided into 10 colors, namely: (1) Y (yellow = yellow), (2) YR (yellow-red), (3) R (red = red), (4) RP (red-purple), (5 ) P (purple = purple), (6) PB (purple-brown), (7) B (brown = brown), (8) BG (grown-gray), (9) G (gray = gray), and ( 10) GY (gray-yellow). Furthermore, each color hue is divided into ranges as follows: (1) hue = 0 to 2.5; (2) hue = 2.5 to 5.0; (3) hue = 5.0 to 7.5; (4 ) hue = 7.5 - 10. This hue value in book written only: 2.5, 5.0, 7.5, and 10.
Based on the book Saoil Color Chart Munsell Hue value is divided into: (1) 5 R, (2) 7.5 R, (3) 10 R, (4) 2.5 YR; (5) 5 YR; (6) 7, 5 YR; (7) 10 YR; (8) 2.5 Y, and (9) 5 Y, ie the most dominant of the spectrum mujlai red (5 R) until at least the dominant spectral yellow (5 Y), while also often added to the colors of the land is reduced (gley), namely: (10) 5 G, (11) 5 GY; (12) 5 BG, and (13) N (neutral).

Value distinguishable from 0 to 8, ie the higher the value indicates the brighter colors (the more the reflected light). Value on sheet book value of the Munsell Soil Color Chart extends vertically from the ground up with the order value of 2, 3, 4, 5, 6, 7, and 8. Figures 2 darkest and brightest figure 8.

Chroma is also divided from 0 to 8, whereby the higher the chroma indicates the purity of the color spectrum or power spectrum is increased. Chroma values in sheet Munsell Soil Color Chart book with horizontal range from left to right order chroma values: 1, 2, 3, 4, 6, 8. Figure 1 is not a pure color and figure 8 purest color spectrum.

Recording soil color can use the Munsell Soil Color Chart book, for example:
(1) soil color is 7.5 YR 5 / 4 (brown), which means that the color of the soil has a value = 7.5 YR hue, value = 5, chroma = 4, which collectively are brown.
(2) Soil color 10 R 4 / 6 (red), which means that the color hue value of land has an R = 10, value = 4, and chroma = 6, which collectively are red.
Furthermore, if found in the soil with several colors, all colors should be mentioned by mentioning also the dominant color of the soil. Ground color will be different when the soil is wet, damp, or dry, so that in determining the color of the soil should be noted whether the land is wet, damp, or dry.
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