Several approaches can be followed to estimate crop water use. Most methods attempt to measure or estimate one or more components of the soil-plant-atmosphere system. Irrigation scheduling methods are therefore planted, soil or atmosphere based. Preferably, a...
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The operation, maintenance and evaluation of systems
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Applying a leaching fraction (LF)
When this approach is followed, the irrigation amount exceeds the measured profile or root zone deficit by a certain fraction. A leaching fraction is usually added to the irrigation amount to leach salts out of the root zone or when water of poor quality (high salt...
Applying a deficit irrigation strategy
Deficit irrigation refers to a water management strategy where, on purpose, the root zone is not refilled to field capacity by irrigation. Soils are ‘leaky systems’, which means that any water above field capacity will percolate or ‘leak’ beyond the root zone and be...
Refill the soil to field capacity (FC)
The concepts of plant available water (PAW), field capacity (FC) and the profile deficit were explained above. FC can be seen as the ‘full point’ of the soil profile, while the deficit is the amount of water required at any time to refill the soil to FC. If the...
How much to irrigate?
After deciding when to irrigate, the irrigation manager can decide whether he/she wants to refill the soil to field capacity (FC), apply a deficit irrigation strategy (DI) or apply a leaching fraction (LF) when determining the irrigation amount.