Soil
Soil is a natural body consisting of layers (soil horizons) that are primarily composed of minerals which differ from their parent materials in their texture, structure, consistency, colour, chemical, biological and other characteristics. It is the unconsolidated or loose covering of fine rock particles that covers the surface of the earth. Soil is the end product of the influence of the climate (temperature, precipitation), relief (slope), organisms (flora and fauna), parent materials (original minerals), and time. In engineering, soil is referred to as regolith, or loose rock material: this is the 'drift deposit' lying on top of the 'solid geology'. However, in horticulture, the term 'soil' is defined as the humic layer of topsoil, or the depth of regolith containing organic material that influences and has been influenced by plant roots and may range in depth from centimetres to many metres. Expressions such as lunar soil or Martian soil are commonly used for extraterrestrial regolith, even though there is no known biological component.
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Famous quotes containing the word soil:
“Men nowhere, east or west, live yet a natural life, round which the vine clings, and which the elm willingly shadows. Man would desecrate it by his touch, and so the beauty of the world remains veiled to him. He needs not only to be spiritualized, but naturalized, on the soil of earth.”
—Henry David Thoreau (1817–1862)
“The constant abrasion and decay of our lives makes the soil of our future growth.”
—Henry David Thoreau (1817–1862)
“The same soil is good for men and for trees. A man’s health requires as many acres of meadow to his prospect as his farm does loads of muck.”
—Henry David Thoreau (1817–1862)