Available water capacity
Encyclopedia
Available water capacity or available water content (AWC) is the range of available water that can be stored in soil and be available for growing crops.
The concept, put forward by Frank Veihmeyer and Arthur Hendrickson, assumed that the water readily available to plants is the difference between water content
at field capacity
(θfc) and permanent wilting point
(θpwp):
Daniel Hillel criticised that the terms FC and PWP were never clearly defined, and lack physical basis, and that soil water is never equally available within this range. He further suggested that a useful concept should concurrently consider the properties of plant, soil and meteorological conditions.
Lorenzo A. Richards
remarked that the concept of availability is oversimplified. He viewed that: the term availability involves two notions: (a) the ability of plant root to absorb and use the water with which it is in contact and (b) the readiness or velocity with which the soil water moves in to replace that which has been used by the plant.
The concept, put forward by Frank Veihmeyer and Arthur Hendrickson, assumed that the water readily available to plants is the difference between water content
Water content
Water content or moisture content is the quantity of water contained in a material, such as soil , rock, ceramics, fruit, or wood. Water content is used in a wide range of scientific and technical areas, and is expressed as a ratio, which can range from 0 to the value of the materials' porosity at...
at field capacity
Field capacity
Field capacity is the amount of soil moisture or water content held in soil after excess water has drained away and the rate of downward movement has materially decreased, which usually takes place within 2–3 days after a rain or irrigation in pervious soils of uniform structure and texture...
(θfc) and permanent wilting point
Permanent wilting point
Permanent wilting point or wilting point is defined as the minimal point of soil moisture the plant requires not to wilt. If moisture decreases to this or any lower point a plant wilts and can no longer recover its turgidity when placed in a saturated atmosphere for 12 hours...
(θpwp):
- θa ≡ θfc − θpwp
Daniel Hillel criticised that the terms FC and PWP were never clearly defined, and lack physical basis, and that soil water is never equally available within this range. He further suggested that a useful concept should concurrently consider the properties of plant, soil and meteorological conditions.
Lorenzo A. Richards
Lorenzo A. Richards
Lorenzo Adolph Richards or known as Ren was one of the 20th century’s most influential minds in the field of soil physics. Richards was born on April 24, 1904, in the town of Fielding, Utah, and received a B.S. and M.A. degree in Physics from Utah State University...
remarked that the concept of availability is oversimplified. He viewed that: the term availability involves two notions: (a) the ability of plant root to absorb and use the water with which it is in contact and (b) the readiness or velocity with which the soil water moves in to replace that which has been used by the plant.
See also
- Field capacityField capacityField capacity is the amount of soil moisture or water content held in soil after excess water has drained away and the rate of downward movement has materially decreased, which usually takes place within 2–3 days after a rain or irrigation in pervious soils of uniform structure and texture...
- Permanent wilting pointPermanent wilting pointPermanent wilting point or wilting point is defined as the minimal point of soil moisture the plant requires not to wilt. If moisture decreases to this or any lower point a plant wilts and can no longer recover its turgidity when placed in a saturated atmosphere for 12 hours...
- Nonlimiting water rangeNonlimiting water rangeThe Non-limiting water range represents the range of water content in the soil where limitations to plant growth are minimal...
- Integral energyIntegral energyIntegral energy is the amount of energy required to remove water from an initial water content \theta_i to water content of \theta_f...