Moisture equivalent is proposed by
Lyman Briggs
Lyman James Briggs (May 7, 1874 – March 25, 1963) was an American engineer, physicist and administrator. He was a director of the National Bureau of Standards during the Great Depression and chairman of the Uranium Committee before America e ...
and McLane (1910) as a measure of
field capacity Field capacity is the amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased. This usually takes place 2–3 days after rain or irrigation in pervious soils of u ...
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
Soil physics is the study of soil's physical properties and processes. It is applied to management and prediction under natural and managed ecosystems. Soil physics deals with the dynamics of physical soil components and their phases as solid ...
, 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
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Available water capacity Available water capacity is the amount of water that can be stored in a soil profile and be available for growing crops. It is also known as available water content (AWC), profile available water (PAW) or total available water (TAW).
The concept, p ...
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Field capacity Field capacity is the amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased. This usually takes place 2–3 days after rain or irrigation in pervious soils of u ...
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Nonlimiting water range The non-limiting water range (NLWR) represents the range of water content in the soil where limitations to plant growth (such as water potential, air-filled porosity, or soil strength) are minimal. John Letey (1985) from UC Riverside introduced the ...
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Pedotransfer function In soil science, pedotransfer functions (PTF) are predictive functions of certain soil properties using data from soil surveys.
The term ''pedotransfer function'' was coined by Johan Bouma as ''translating data we have into what we need''. The mos ...
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Permanent wilting point
Permanent wilting point (PWP) or wilting point (WP) is defined as the minimum amount of water in the soil that the plant requires not to wilt. If the soil water content decreases to this or any lower point a plant wilts and can no longer recover ...
References
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* {{cite book , last = Lyman , first = James Briggs , author-link = Lyman James Briggs , author2=H. L. Shantz , title = The wilting coefficient for different plants and its indirect determination , publisher = USDA Bureau of Plant Industry , year = 1912 , id = Bulletin 230
Soil physics
Equivalent units