Weekly Irrigation Requirements – Macalister Irrigation District

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Macalister ETo Update

9th January to 15th January 2020

    • Flood irrigation interval for the last week was 9 days
    • Spray irrigators needed to have applied 31 mm of irrigation water for the week
    • The predicted weekly pasture water use for the MID in the next week is 27 mm, Yarram 27 mm and Bairnsdale 28 mm. 
    • Glenmaggie is at 52.9%
    * These figures are approximate and do not take into account rainfall on farm*

The Odd Spot

Grants of $75,000 to get fire-hit farms back up and running
The Federal Government has announced with a one-off $75,000 grant for fire-affected farmers for essentials like fodder and water, generators, farm infrastructure including fences, solar panels, paying vets, and disposal of dead stock. Further details would be announced as soon as state-based delivery arrangements are confirmed. More details https://bit.ly/35Z2KUq

Gippsland Irrigation Expo returns in 2020! 
There are only 6 weeks to go until the Gippsland Irrigation Expo! All the big names are coming, as well as many of our very own locals, so it is an event not to be missed. Entry is free, so put Wednesday, March 4th into your calendar, and come along to the Sale Showgrounds from 8:30am till 4:30pm. More information will be available soon.

Irrigation Discussion Group
Come along to a twilight get-together of the Irrigation Discussion Group at Benn Thexton‘s farm, 406 Cobains Road, Cobains. We’ll meet at 6.30ishpm for a 7pm paddock-walk, followed by an 8pm BBQ. Topic will be “Options for the rest of the season”.  Kids are welcome. For catering purposes, please let Janice know on 0437 282 315.

 ETo – Last Week Totals

Location ETo mm Effective rain* mm (R) Dairy pasture coefficient Required irrigation mm
 (ETₒ – R)
Tinamba 24.8 8.8 1 16.0
Boisdale 29.0 13.4 1 15.6
Denison 32.2 0 1 32.2
Cowwarr 29.3 5.6 1 23.7
East Sale 37.7 8.2 1 29.5
Bairnsdale** 40.6 11.4 1 29.2

Tip:  To convert mm to megalitres/ha, divide by 100.  Eg. 50mm = 0.5ML /ha.
* Effective rainfall = daily rainfall minus 2mm.
ETₒ   and the “crop coefficient” (conversion factor) of 1.0 applies to a healthy productive pasture 12 cm high.
** Bairnsdale’s Data is not included when doing any of the below calculations

MID average daily pasture water use over the last week was 4.4 mm/day.
The approximate MID flood irrigation interval based on last week’s daily pasture water use rate was 9 days. (This figure assumes that 30 mm of readily available water is held in the pasture root zone divided by the 4.4 mm/day = 7 days and then add an extra two days to account for waterlogging). This does not take into account any rain your farm may have got during the week which will extend the interval.

Spray irrigators in the MID needed to have applied on average 31 mm of irrigation water for the week to meet pasture water use (4.4 x 7). This irrigation figure does not take into account any rainfall on your farm, which must be subtracted from the required irrigation figure, and assumes that the spray irrigation system is applying water at 100% uniformity. This figure may be greater depending on specific spray irrigation system uniformity.


For Thursday 16 January to Wednesday 22 January 

Location Predicted weekly pasture water use (mm/ha) Predicted weekly pasture water use (ML/ha) Predicted daily pasture water use (mm/day)
MID 27 0.27 3.8
Yarram 27 0.27 3.8
Bairnsdale 28 0.28 4.0



The intention of this service is not for the information to be used in isolation when making decisions about irrigation scheduling.
This publication is provided solely for information purposes and no representation or warranty is made as to its quality, accuracy, completeness, suitability or fitness for any particular purpose. You should make your own inquiries as to its appropriateness and suitability for your particular circumstances. The State of Victoria as represented by its Department of Economic Development, Jobs, Transport and Resources accepts no duty of care and disclaims all liability in relation to use of this publication.

AgVic also provides weekly ET email updates for North East Victoria (contact dennis.watson@ecodev.vic.gov.au), Northern Victoria (robert.oconnor@ecodev.vic.gov.au) and the Mallee (maxine.schache@ecodev.vic.gov.au).

You can also follow on Twitter and Facebook.

Further information:

For more detail about using evapotranspiration data refer to this Agriculture Victoria fact sheet “What is evapotranspiration and how do I use it to schedule irrigationsor this scientific paper.


If you would like to subscribe to this email or if you have any questions, comments or feedback related to this email service please don’t hesitate to contact Alexis Killoran on the email below.

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