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:
“Let him
Who was love’s teacher teach you too love’s cure;
Let the same hand that wounded bring the balm.
Healing and poisonous herbs the same soil bears,
And rose and nettle oft grow side by side.”
—Ovid (Publius Ovidius Naso)
“The civilized nations—Greece, Rome, England—have been sustained by the primitive forests which anciently rotted where they stand. They survive as long as the soil is not exhausted. Alas for human culture! little is to be expected of a nation, when the vegetable mould is exhausted, and it is compelled to make manure of the bones of its fathers. There the poet sustains himself merely by his own superfluous fat, and the philosopher comes down on his marrow-bones.”
—Henry David Thoreau (1817–1862)
“If the accumulated wealth of the past generations is thus tainted,—no matter how much of it is offered to us,—we must begin to consider if it were not the nobler part to renounce it, and to put ourselves in primary relations with the soil and nature, and abstaining from whatever is dishonest and unclean, to take each of us bravely his part, with his own hands, in the manual labor of the world.”
—Ralph Waldo Emerson (1803–1882)