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Irrigation, how much is enough?

Irrigation, how much is enough?
irrigation management is critical but straight forward

Irrigation is on everyone’s mind at the moment, but how much is enough?

As a general rule greens lose approximately 3-4mm of moisture per dry day to evapo-transpiration, although this can vary with conditions; that’s approximately 25mm or 1 inch per week.

Again a very general rule is that many of the more popular automatic sprinkler systems will apply around 1mm of water for every 2 minutes of run time.

So again as a general rule to replace a week’s worth of losses you should be running the sprinklers for around 50 minutes in the week.

Now I will add a qualification or four to that:

  1. requirements can vary widely depending on location and conditions.
  2. don’t apply light applications on a nightly basis, try to group these into heavier and less frequent applications for best effect.
  3. try to move to a water balance sheet type system to manage irrigation more accurately…it will pay off quickly
  4. don’t rely on a typical bowling green irrigation system to apply water evenly or in sufficient volume…always check and measure what you are doing.

Irrigation management and water balance sheets in my book Performance Bowling Greens.

any questions please ask!


  1. Darren Henderson says:

    Hi John,
    With all this heavy rain the Current SMD on the water balance sheet is a high negative number. Do you keep adding the ET & subtracting the rainfall or do you return the SMD to zero?
    Since the average ET is 3 to 6mm it would take about 10 days of sunshine before the green returned to field capacity.
    Thanks for your help,

  2. John says:

    Hi Darren
    Good to hear from you and good to see you are using a water balance sheet, even though things are well out of balance this year.

    Regardless of the amount of rainfall, the soil will always return to field capacity quickly as long as drainage isn’t impeded, for example by a very high water table.
    Field capacity is the point reached when the capillary (micro) pore space in the soil is full. The macro or aeration pore space will always drain down quickly to leave the soil at field capacity.

    Having said all of that if you are sure that the green is at field capacity, you could start from zero again.



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