Glossary

 

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Water retention

The ability of soil to hold water for a period that is longer than infiltration, normally 48h in a freely draining soil. It strongly depends on organic matter and bulk density. Soil texture also has an influence on water retention.


Water table

The upper surface of ground water or that level in the ground where the water is at atmospheric pressure.


Weathering

The breakdown and changes in rocks and sediments at or near the Earth's surface produced by biological, chemical, and physical agents or combinations of them.


Wetland

A transitional area between aquatic and terrestrial ecosystems that is inundated or saturated with water for long enough periods to produce hydric soils and support hydrophytic vegetation. See also bay, bog, fen, marsh, pocosin, swamp, and tidal flats.


Wilting point

Soil moisture content when the rate of absorption of water by plant roots is too slow to maintain plant turgidity and permanent wilting occurs. The average moisture tension at the outside surface of the moisture film around soil particles when permanent wilting occurs is 15 atmospheres or 1500kPa.



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