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What is soil


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What is soil

  1. 1. What is soil? You have 3 minutes to develop a group consensus definition.
  2. 2. Merriam-Webster Online Dictionary <ul><li>Main Entry: 3 soil, noun 1 : firm land : EARTH 2 a : the upper layer of earth that may be dug or plowed and in which plants grow b : the superficial unconsolidated and usually weathered part of the mantle of a planet and especially of the earth 3 : COUNTRY, LAND <our native soil > 4 : the agricultural life or calling 5 : a medium in which something takes hold and develops </li></ul>
  3. 3. Wikipedia – The Free Encyclopedia <ul><li>Soil is material capable of supporting plant life. Soil forms through a variety of soil formation processes , and includes weathered rock &quot;parent material&quot; combined with dead and living organic matter and air. </li></ul><ul><li>Soils are vital to all life on Earth because they support the growth of plants , which supply food and oxygen and absorb carbon dioxide and nitrogen . </li></ul>
  4. 4. OneLook Dictionary Search <ul><li>Quick definitions ( soil ) </li></ul><ul><li>noun :    the part of the earth's surface consisting of humus and disintegrated rock </li></ul><ul><li>noun :    the geographical area under the jurisdiction of a sovereign state (Example: &quot;American troops were stationed on Japanese soil&quot; ) </li></ul><ul><li>noun :    material in the top layer of the surface of the earth in which plants can grow (especially with reference to its quality or use) (Example: &quot;Good agricultural soil&quot; ) </li></ul><ul><li>noun :    the state of being covered with unclean things </li></ul><ul><li>verb :    make soiled, filthy, or dirty (Example: &quot;Don't soil your clothes when you play outside!&quot; ) </li></ul>
  5. 5. <ul><li>What’s the difference between soil and dirt? Dirt is what you find under your fingernails. Soil is what you find under your feet. Think of soil as a thin living skin that covers the land. It goes down into the ground just a short way. Even the most fertile topsoil is only a foot or so deep. Soil is more than rock particles. It includes all the living things and the materials they make or change. </li></ul>
  6. 6. , cont’d <ul><li>There is no soil on Mars or Venus. How come? Those planets have plenty of rocks. Mars has windstorms that erode rocks into dust. Venus has an acid atmosphere that cooks rocks into new chemicals. But there's still something missing. Without life, there is no soil. Living things haven't just made a home in the soil on our planet. Life actually made the soil as we know it. </li></ul>
  7. 7. Definitions (simplified) <ul><li>Soil is a dynamic, heterogeneous, three-phase, porous media </li></ul><ul><ul><li>Perspective: Soil Physics </li></ul></ul><ul><li>Soil is the outer layer of the earth’s crust capable of supporting plant growth (Pearson, 1967, Principles of Agronomy) </li></ul><ul><ul><li>Perspective: Botany, Agronomy, Horticulture, ... </li></ul></ul><ul><li>Soil is unconsolidated, surficial material. </li></ul><ul><ul><li>Perspective: Geology, Engineers </li></ul></ul>
  8. 8. Definitions, Byers, et al., Formation of Soil, 1938* <ul><li>Soils are natural media for the growth of plants. They are mixtures of fragmented and partly or wholly weathered rocks and minerals, organic matter, water, and air, in greatly varying proportions, and have more or less distinct layers or horizons developed under the influence of climate and living organisms…Soils are dynamic in character …the product of the action of climate and living organisms upon the parent material, as conditioned by the local relief. </li></ul><ul><li>*Yearbook of Agriculture </li></ul>
  9. 9. Definitions, Simonson, What Soils Are, 1957* <ul><li>The soil is the link between the rock core of the earth and the living things on its surface. It is the foothold for the plants we grow. </li></ul><ul><li>The soil mantle of the earth is far from uniform, but all soils have some things in common. </li></ul><ul><ul><li>Every soil consists of mineral and organic matter, water, and air … </li></ul></ul><ul><ul><li>Every soil occupies space ... </li></ul></ul><ul><ul><li>Every soil has a profile … </li></ul></ul><ul><li>*Yearbook of Agriculture </li></ul>
  10. 10. Definitions, Hillel, Introduction to Soil Physics, 1982 <ul><li>Soil refers to the weathered and fragmented outer layer of the earth’s terrestrial surface. </li></ul><ul><li>The soil is a heterogeneous, polyphasic, particulate, disperse, and porous system, in which the interfacial area per unit volume can be very large. The disperse nature of the soil and its consequent interfacial activity give rise to such phenomena as adsorption of water and chemicals, ion exchange, adhesion, swelling and shrinking, dispersion and flocculation, and capillarity. </li></ul>
  11. 11. Definitions, Daubenmire, Plants and Environment, 1974* <ul><li>Soil …any part of the earth’s crust in which plants are anchored: the muddy bottoms of ponds, porous rock surfaces into which cryptogams send their rhiziods, peat, raw gravel deposited by glaciers, etc. </li></ul><ul><li>Soil may be defined as the weathered superficial layer of the earth’s crust with which are mingled living organisms and products of their decay. </li></ul><ul><li>*A Textbook of Autecology, 3 rd ed. </li></ul>
  12. 12. Definitions, Spangler & Handy, 1982, Soil Engineering <ul><li>Soils are natural materials which occur in infinite variety over the earth and whose engineering properties may vary widely from place to place within the relatively small confines of a single engineering project … </li></ul><ul><li>The properties of soils are continuously changing as the amount of moisture fluctuates and other environmental influences vary… and may change dramatically under load </li></ul><ul><li>Soil is used as construction material … </li></ul>
  13. 13. Definition, Soil Science Glossary, SSSA <ul><li>(i) The unconsolidated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants. </li></ul>
  14. 14. Definition, Soil Science Glossary, SSSA, cont’d <ul><li>(ii) The unconsolidated mineral or organic matter on the surface of the earth that has been subjected to and shows effects of genetic and environmental factors of: climate (including water and temperature effects), and macro- and microorganisms, conditioned by relief, acting on parent material over a period of time. A product-soil differs from the material from which it is derived in many physical, chemical, biological, and morphological properties and characteristics. </li></ul>
  15. 15. Definition, Joffe, 1949, modified by Birkeland, 1999 <ul><li>Soil is a natural body consisting of layers (horizons) of mineral and/or organic constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical properties and their biological characteristics. </li></ul>
  16. 16. Definition, Soil Taxonomy, 2 nd ed. <ul><li>Soil is a natural body comprised of solids (minerals and organic matter), liquid, and gases that occurs on the land surface, occupies space, and is characterized by one or both of the following: horizons, or layers, that are distinguishable from the initial material as a result of additions, losses, transfers, and transformations of energy and matter or the ability to support rooted plants in a natural environment. </li></ul>
  17. 17. Definition, Soil Taxonomy, 2 nd ed. <ul><li>The upper limit of soil is the boundary between soil and air, shallow water, live plants, or plant materials that have not begun to decompose. Areas are not considered to have soil if the surface is permanently covered by water too deep (typically more than 2.5 meters) for the growth of rooted plants. </li></ul>
  18. 18. Definition, Soil Taxonomy, 2 nd ed. <ul><li>The lower boundary that separates soil from the nonsoil underneath is most difficult to define. Soil consists of horizons near the earth's surface that, in contrast to the underlying parent material, have been altered by the interactions of climate, relief, and living organisms over time. Commonly, soil grades at its lower boundary to hard rock or to earthy materials virtually devoid of animals, roots, or other marks of biological activity. For purposes of classification, the lower boundary of soil is arbitrarily set at 200 cm. </li></ul>