Physics:Moisture equivalent
Moisture equivalent is proposed by Lyman Briggs and McLane (1910) as a measure of field capacity for fine-textured soil materials. Moisture equivalent is defined as the percentage of water which a soil can retain in opposition to a centrifugal force 1000 times that of gravity. It is measured by saturating sample of soil 1 cm thick, and subjecting it to a centrifugal force of 1000 times gravity for 30 min. The gravimetric water content after this treatment is its moisture equivalent. This concept is no longer used in soil physics, replaced by field capacity.
Lyman Briggs and Homer LeRoy Shantz (1912) found that:
Moisture Equivalent = 0.02 sand + 0.22 silt + 1.05 clay
Note: volume of water stored in root zone is equal to the depth of water in root zone (Vw=Dw)
See also
- Available water capacity
- Field capacity
- Nonlimiting water range
- Pedotransfer function
- Permanent wilting point
References
- Lyman, James Briggs; J. W. McLane (1907). The moisture equivalents of soils. USDA Bureau of Soils. Bulletin 45.
- Lyman, James Briggs; J. W. McLane (1910). "Moisture equivalent determinations and their application". American Society of Agronomy Proceedings (American Society of Agronomy) 2: 138–147. doi:10.2134/agronj1910.00021962000200010024x.
- Lyman, James Briggs; H. L. Shantz (1912). The wilting coefficient for different plants and its indirect determination. USDA Bureau of Plant Industry. Bulletin 230.
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