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Unformatted text preview: SOIL WATER POTENTIAL Read : Within pages 105 to 125 Introduction to Environmental Soil Ph ysics Units for Ex pressin g Soil Water Potentials Pressure and gravitational potentials are often expressed in terms of the hei ght of a column of water , which will develop an equivalent pressure or suction. Matric and osmotic potentials are frequently expressed in terms of kPa (centimeters or meters of water ) and various other units of pressure. The following conversions are useful: 1 bar = 0.987 atmosphere = 1,017 cm of H 2 O = 10-1 megapascal, MPa (10 6 Pa). ALSO 1 cbar = 1 kPa = 10 cm of H 2 O. • 1) Gravitational potential, M g — depends only on elevation above or below a reference point. Measure with GPS unit, ruler, tape, etc. • 2) Pressure potential, M p — depends on the length of the column of water above a reference point. • As this is often called the piezometric head, obviously it can be measured with a piezometer (often abbreviated as h or p as expressed in cm or m of water)....
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This note was uploaded on 08/08/2008 for the course SS 322 taught by Professor Lowery during the Spring '08 term at University of Wisconsin Colleges Online.
- Spring '08