Soil

Name:
Soil
Detailed information:
(1) A mixture of inorganic matter derived from weathered rocks and organic components resulting from decay of prior vegetation. Eight elements are present in the inorganic component in excess of 1% (oxygen, silicon, aluminum, iron, calcium, potassium, magnesium, and sodium), most in the ionized state. Water and air are also present, either in the voids between the particles or adsorbed on their surfaces. Many other elements occur in lower percentages, including trace elements in concentration of less than 1000 ppm. Some of these, e.g., boron (about 20 ppm), are essential for plant nutrition. Both nitrogen and phosphorus are associated with the organic content. The concentration of these is a fraction of 1% of each, but they play a vital part in plant and animal life. The pH of soils varies widely with location; some soils are as low as pH 4.5 (very acid) and others as high as pH 10 (strongly alkaline). For most crops the pH ranges around the neutral point (6.5–7.5). Texturally, soils are classified on the basis of their content of sand, silt, and clay. Those having 45–50% sand and 20–28% clay are called loams, those with more than 50% sand are called sandy, and those with more than 28% clay are in the clay group. Technologists consider soil as being made up of layers, known as horizons, each having a characteristic composition and physical properties; the spectrum of these horizons is called the soil profile. Organic matter is usually excluded from the profile.(2) In textile literature, any foreign matter present in or on fiber or fabric, i.e., dirt, oil, grease, etc. These are usually removable by the action of soap, synthetic detergents, or organic solvents.