Soil

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Growth of the soil by hamsun.jpg

Etymology

Middle English, from Anglo-French, soil, piece of land, from Vulgar Latin *solium, alteration of Latin solea sole, sandal, foundation timber

Definitions

  • 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

Description

Soil is a natural body consisting of layers (soil horizons) of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics.

It is composed of particles of broken rock that have been altered by chemical and environmental processes that include weathering and erosion. Soil differs from its parent rock due to interactions between the lithosphere, hydrosphere, atmosphere, and the biosphere.

It supports a complex ecosystem, which supports the plants on the surface and creates new soil by breaking down rocks and sand. This microscopic ecosystem has co-evolved with the plants to collect and store water and nutrients in a form usable by plants.

Soil particles pack loosely, forming a soil structure filled with pore spaces. These pores contain soil solution (liquid) and air (gas). Accordingly, soils are often treated as a three state-system. Most soils have a density between 1 and 2 g/cm³. Soil is also known as earth: it is the substance from which our planet takes its name. Little of the soil composition of planet Earth is older than the Tertiary and most no older than the Pleistocene. In engineering, soil is referred to as regolith, or loose rock material.

See also

Quote

For only when you experience the stillness are you in complete knowledge of His presence and only as you carry your understanding of grace with you into your arena are you capable of maintaining that quality which allows you to prevail with men in such a way as to maintain your own sense of balance and solidarity -- that is to say: your head in the clouds and your feet on the ground -- and this condition is evidence of a well-unified personality operating in the fullest capacity known to him at that time. - Tomas