First – an introduction to uniformity

One of the key reasons people use drip irrigation is uniformity – all the plants receive an equal amount of water, which in turn leads to better crop uniformity at harvest.

Uniformity is important as the drip irrigation supplies:

  • water

  • fertilizers

  • pesticides

You want the plant with the nearest emitter to receive the same application as the plant at the farthest emitter.

Emission uniformity (EU)
  • More commonly used for drip tapes
  • There are three formulas for measuring EU. Below is the calculation for classic EU:
     

     
  • The higher the EU, the better the uniformity
  • Goal: EU of >.90

Qmin = the minimum emitter flow in the block
Qavg=the average emitter flow in the block
Cv=The coefficient of variation of emitter discharges as published by the manufacturer (standard deviation of flow rates/mean flow rate)

 
Flow variation (FV)
  • More commonly used for drip lines, and outside of USA
  • Measures the variation of flow considering the variance between the highest flow and the lowest flow of all drippers
     

     
  • The lower the FV, the better the uniformity
  • Goal: FV of 10% or lower

Qmin = the minimum emitter flow in the block
Qmax=the maximum emitter flow in the block

 

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