The color of the soil is its important characteristic, since it determines whether it belongs to a certain type. Before you understand what determines the dark or gray color of the soil, you need to familiarize yourself with the set of earthen material. A change in soil shade means a change in soil properties. It is noteworthy that in ancient times farmers judged its fertility by the color of the soil.
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What determines the color of soils
Often it is the shade of the earth that determines its name (chernozem, gray forest soil, red soil, chestnut soil, podzolic soil). The amount and color of the substances that make up the soil significantly affect its color.
Common components:
- The main organic substance containing the maximum nutrients for plants is humus. The more it is, the darker the shade of the soil layer.It is the humus content that determines fertility. There are several types of humus: podzolic, sod-podzolic, chernozem. Basic ground tones: gray, dark gray, black;
- Mica materials, illite (hydromuscovite) give the earth a brownish tone. Often found in soils formed in areas of rock eruptions;
- The red tone of the soil is given by compounds of iron oxides. The mineral is necessary for plants because it takes part in oxygen metabolism and redox processes. Lack of iron provokes a slowdown in plant growth and chlorophyll synthesis. A significant content of iron oxide gives the earth a reddish-brown, red or “rusty” tone. With a small amount of iron oxide, the soil becomes yellowish or orange in color;
- the soil is painted in light colors with silica and feldspar. A light whitish tint is characteristic of soils containing gypsum and water-soluble salts.
Naturally, the structure of the earth also affects the shade. Therefore, the blocks appear darker than pulverized or structureless soil. Also, the color of the soil changes after watering (wet is darker than dry). Therefore, it is recommended to evaluate the color based on the depth section.
Determination of color
When determining this characteristic, it is customary to distinguish between the main tone and shades, since in natural conditions the soil rarely has a single specific color. Common options: dark brown, light brown, dark gray. As a rule, the dominant color is placed last. Sequence for determining color:
- set the predominant color. Usually the dark color is due to the presence of pigment;
- determine the tone saturation (dark or light);
- the presence of shades is noted (brown-brown, brownish-gray).
To evaluate color, several methods are used: rotating Maxwell disks, visual analyzer, visual description, photometric, visual comparison with a scale. Most often, visual comparison or description is used to evaluate soils.
The shade reflects the characteristics of the soil-forming process. Therefore, a change in color indicates a change in the internal properties of the soil. It is also necessary to take into account that the color of soil horizons is heterogeneous; transitional or mixed tones are often found.
