Soil is an important natural resource that covers much of the earth's land surface. All life on earth depends on the soil as a direct or indirect source of food. Plants are rooted in the soil and obtain nutrients (nourishing substances) from it. Animals get nutrients from plants or from animals that eat plants. Certain microbes in the soil cause dead organisms to decay, which helps return nutrients to the soil. In addition, many kinds of animals find shelter in the soil.
Soil contains mineral and organic particles, other plant and animal matter, and air and water. The contents of soil change constantly. There are many kinds of soils, and each has certain characteristics, including colour and composition. The kind of soil in an area helps determine how well crops grow there. Soil forms slowly and is destroyed easily, and so it must be conserved so it can continue to support life.
Soil begins to form when environmental forces break down rocks and similar materials that lie on or near the earth's surface. Pedologists call the resulting matter parent material. As soil develops through the centuries, organic material collects, and the soil resembles the parent material less and less. Glaciers, rivers, wind, and other environmental forces may move parent material and soil from one area to another.
Soil formation differs according to the effects of various environmental factors. These factors include (1) kinds of parent material, (2) climate, (3) land surface features, (4) plants and animals, and (5) time.
The soils of farmlands, grazing lands, and forestlands provide many products and recreational areas, so it is important to conserve them. Soil conservationists work to ensure the wise use of these soils.
Rain water, wind, and other natural forces gradually wear away the soil. This process, called erosion, normally occurs very slowly. But people have greatly increased the...
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