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:
“But men labor under a mistake. The better part of the man is soon ploughed into the soil for compost. By a seeming fate, commonly called necessity, they are employed, as it says in an old book, laying up treasures which moth and rust will corrupt and thieves break through and steal. It is a fool’s life, as they will find when they get to the end of it, if not before.”
—Henry David Thoreau (1817–1862)
“A man’s destination is not his destiny,
Every country is home to one man
And exile to another. Where a man dies bravely
At one with his destiny, that soil is his.”
—T.S. (Thomas Stearns)
“Ah! never shall the land forget
How gushed the life-blood of her brave—
Gushed, warm with hope and courage yet,
Upon the soil they fought to save.”
—William Cullen Bryant (1794–1878)