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The energy required per unit mass of water vaporized. (J g −1) L v = Volumetric latent heat of vaporization. The energy required per unit volume of water vaporized. (L v = 2453 MJ m −3) E = Mass water evapotranspiration rate (g s −1 m −2) ET = Water volume evapotranspired (mm s −1) Δ = Rate of change of saturation specific humidity ...
The first MPR nozzles, the MP Rotator, were produced by Nelson Irrigation in 2003, and acquired by Hunter Industries in 2007. [4] [5] [6] Since then the popularity of these highly uniform yet low application sprinklers has caused every major sprinkler manufacturer to produce their own version of an MPR sprinkler, including Rain Bird [7] and Toro.
The Penman equation describes evaporation (E) from an open water surface, and was developed by Howard Penman in 1948. Penman's equation requires daily mean temperature, wind speed, air pressure, and solar radiation to predict E. Simpler Hydrometeorological equations continue to be used where obtaining such data is impractical, to give comparable results within specific contexts, e.g. humid vs ...
Distribution uniformity or DU in irrigation is a measure of how uniformly water is applied to the area being watered, normally expressed as percentage, and not to be confused with efficiency. [1] The distribution uniformity is often calculated when performing an irrigation audit. The DU should not be confused with the coefficient of uniformity ...
The sodium adsorption ratio (SAR) is an irrigation water quality parameter used in the management of sodium-affected soils.It is an indicator of the suitability of water for use in agricultural irrigation, as determined from the concentrations of the main alkaline and earth alkaline cations present in the water.
The Blaney–Criddle equation is a relatively simplistic method for calculating evapotranspiration.When sufficient meteorological data is available the Penman–Monteith equation is usually preferred.
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This usually occurs two to three days after rain or irrigation in pervious soils of uniform structure and texture. The nominal definition of field capacity (expressed symbolically as θ fc) is the bulk water content retained in soil at −33 kPa (or −0.33 bar) of hydraulic head or suction pressure.