Soil

• Soil, the loose material that covers the land surfaces of Earth and supports the growth of plants.
• In general, soil is an unconsolidated, or loose, combination of inorganic and organic materials.
• The inorganic components of soil are principally the products of rocks and minerals that have been gradually broken down by weather, chemical action, and other natural processes.
• The organic materials are composed of debris from plants and from the decomposition of the many tiny life forms that inhabit the soil.Soils vary widely from place to place.
• Many factors determine the chemical composition and physical structure of the soil at any given location.
• The different kinds of rocks, minerals, and other geologic materials from which the soil originally formed play a role.
• The kinds of plants or other vegetation that grow in the soil are also important.
• Topography—that is, whether the terrain is steep, flat, or some combination—is another factor.
• In some cases, human activity such as farming or building has caused disruption.
• Soils also differ in color, texture, chemical makeup, and the kinds of plants they can support.
• Soil actually constitutes a living system, combining with air, water, and sunlight to sustain plant life.
• The essential process of photosynthesis, in which plants convert sunlight into energy, depends on exchanges that take place within the soil.
• Plants, in turn, serve as a vital part of the food chain for living things, including humans.
• Without soil there would be no vegetation—no crops for food, no forests, flowers, or grasslands. To a great extent, life on Earth depends on soil.