Irrigation Scheduling Calculator
Instructions for the Irrigation Scheduling Calculator
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Principles of Irrigation

 Select a Crop:

Kc Source:

    English Units      Metric Units                          

Reference Evapotranspiration (ETo):

 in./day or period      Data Source:

Crop Coefficient (Kc):

 Get Kc for a month

Distribution Uniformity (DU):

  %

Leaching Requirement (LR):

  %

Method:

 Trees per Acre: Tree Spacing by ft.

Number of Emitters per Tree:

Surface area under tree canopy (ft2):

  (enter only when surface area covered by canopy is less than 65%)

Emitter Output (Gal/Hour):

Grove Size (acres):
  All fields with yellow boxes must be filled out, white fields are optional.
  Click on 'Calculate' after any changes are made to recompute totals.

Water per tree per day or period:

 gallons

Watering time per tree per day or period:

 hours, minutes

Total Water Requirements for Grove:

 gallons

Allocated Water for Grove:

 gallons

Shortfall:

 gallons
   
The expanded irrigation calculator:
The irrigation calculator has been expanded to provide the user more variables to consider when scheduling water usage. These include:
The ability to vary the DU to examine how improving irrigation uniformity can conserve water
The ability to designate canopy coverage (i.e. young trees, tree removal or stumped trees)
The ability to designate both the number of emitters per tree and their output to account for multiple emitters per tree

Background:
The water allocation for farmers in the MWD-supplied water districts of southern CA will be cut by 30% beginning Jan 1, 2008. Most avocado groves affected by the cuts are planted on hillsides with shallow decomposed granite soils with low holding water capacity. The avocado requires approximately 3-4 acre feet per year. Additionally, avocado is the most salt sensitive tree crop and requires careful water and leaching management to avoid yield decline due to the effect of salts.
Irrigation management on hillsides is difficult. A key factor in irrigation efficiency is the DU (distribution uniformity). It is not unusual to find groves with DU of 65% or less. The main reasons for the low DU are poor pressure regulation and inadequate infrastructure design (often due to conversion from low volume drip to greater output micro emitters).
   
Created by Reuben Hofshi and Shanti Hofshi
Copyright © The Hofshi Foundation 2006-2007 - All Rights Reserved
This calculator is a revision of the CIMIS calculator by R. Hofshi,
S. Hofshi and B. Faber (www.avocado.org).