Irrigation in the Pacific Northwest

Irrigation Frequency

This calculates the maximum interval allowed between irrigations. This is dependent on soil type, root zone depth (the readily available soil water), and the water use rate of the crop, which changes drastically over a season. Learn more about the units used on this page.

Soil's Available Water Holding Capacity:
Root Zone Depth:
Management Allowable Depletion (as a decimal):
Crop Water Use Rate:
Practical Use Irrigation Frequency:



The Equation

This is the formula this calculator uses to determine the suggested irrigation frequency.


= Suggested irrigation frequency (day)

= Soil's available water holding capacity (in/ft)

= Root Zone Depth (ft)

= Management Allowable Depletion (decimal, or %/100)

= Crop water use rate (in/day)






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