The purpose of the Irrigation calculator is to help manage irrigation scheduling for avocado orchards with at least 65% of the canopy covering the ground. The calculator will work well for any other crop, just input the corresponding Crop coefficient (Kc). 

There are certain values you need to know:

• Tree spacing in feet or meters
• The output of your emitters  in gallons or liters per hour
• The Distribution Uniformity (DU) of your irrigation system
• The water quality in terms of salinity or Electrical Conductivity (EC) from which a Leaching Requirement (LR) could be ascertained
• The Reference Evapotranspiration (ETo) values available from your local CIMIS station, other weather stations or evaporation pan.