AUTO_IDATE - Automatic Irrigation Date

Calculates the irrigation dates based on the cumulative growing degree days (GDD). Each irrigation event occurs when a target GDD (C) is accumulated. The function assumes that the default irrigation operation code IR001. This code could be replaced with other value by add additional DOME command (example #2) GDD Calculation sample can be found here.

Inputs:

• Number of irrigation events
• Base temperature for calculating Growing Degree Day (C)
• Target GDD for #1 irrigation (C-d)
• List of irrigation amount (IRVAL) for #1 irrigation (mm)
• Target GDD for #2 irrigation (C-d)
• List of irrigation amount (IRVAL) for #2 irrigation (mm)
• Target GDD for #n irrigation (C-d)
• List of irrigation amount (IRVAL) for #n irrigation (mm)

Implicit Inputs (i.e., available in the data):

• Weather data
• Planting date

Outputs:

• List of irrigation events

Procedure:

 /* Loop the daily weather data to calculate GDD */ 
 j = 0
 sumGdd = 0
 Loop i from PDATE to last day of weather
   gdd = average(TMAX[i], TMIN[i]) - baseTemperature
   If gdd > 0
     sumGdd += gdd
   End If   
   /* If the cumulative GDD is no less than target value,
      then let the date be the IDATE and reset the sum to calculate the next IDATE */
   If sumGdd >= GDD[j]
     CreateIrrigationEvent(W_DATE[i], IRVAL[j], "IROO1")
     sumGdd = 0
   End If
 End Loop

Calculation might fail if there is insufficient daily weather data. In that case, the function will only generate the irrigation events as possible with the provided weather data.

Examples:

Example #1 Two irrigation events are added to a dataset.

&, FILL, IDATE, AUTO_IDATE(), 2, 5, 400, 40, 160 50

This will add two irrigation events in the data set as follows, (calculated date depends on weather data):

[
  {"event"="irrigation", "date"="19800405", "irval"="40", "irop"="IR001"},
  {"event"="irrigation", "date"="19800505", "irval"="50", "irop"="IR001"}
]

Example #2 Generate two irrigation events with IR004 (Sprinkler) operation code

&, FILL, IDATE, AUTO_IDATE(), 2, 5, 400, 40, 160 50
&, REPLACE, IROP, IR004

The output is as follows:

[
  {"event"="irrigation", "date"="19800405", "irval"="40", "irop"="IR004"},
  {"event"="irrigation", "date"="19800505", "irval"="50", "irop"="IR004"}
]

Example #3 Replace original irrigation events with new generated irrigation events

&, REPLACE, IDATE, AUTO_IDATE(), 2, 5, 400, 40, 160 50

More Samples: The following DOME spreadsheet uses this function: Machakos Overlay DOME

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