Submitted to: Encyclopedia of Water Science
Publication Type: Literature Review
Publication Acceptance Date: October 5, 2002
Publication Date: August 8, 2003
Citation: LOGSDON, S.D. SOIL WATER ENERGY CONCEPTS. ENCYCLOPEDIA OF WATER SCIENCE. 2003. P. 868-870. Technical Abstract: The soil water hydraulic pressure head is composed of matric, overburden, and hydrostatic pressures. The soil solution will flow from higher hydraulic pressure heads to lower hydraulic pressure heads. Piezometers are used to measure the hydrostatic pressure head, and tensiometers are used to measure the negative matric pressure head. The osmotic pressure head is due to solutes in the soil water. Pure water in the soil will move from higher osmotic pressure heads to lower osmotic pressure heads, usually caused by semi-permeable membranes. Thermocouple psychrometers can be used to measure a combination of matric and osmotic pressure heads.