Weekly Irrigation Requirements – Macalister Irrigation District

Macalister ETo Update

26 September to 2 October 2019

  • Flood irrigation interval for the last week was 11 days
  • Spray irrigators needed to have applied on average 24mm of irrigation water for the week
  • The predicted weekly pasture water use for the MID in the next week is 25 mm
  • Lake Glenmaggie is at 92.2%

* These figures are approximate and do not take into account rainfall on farm*

The Odd Spot

Agriculture Energy Investment Plan/Grants
Agriculture Victoria is currently running a grant which is available to farmers that spend over $8000 in energy costs (electricity, diesel, lpg etc) annually.
There are two main types.

 Feature  Type 1  Type 2
 Minimum energy spend  $8,000  $25,000
 Grant Available  Up to $50,000  $50,000 to $250,000
 Required cost share  Farmer to Govt 1:1  Farmer to Govt 1:1

A third type is also available, with a grant of $250,000 to $1,000,000 available by an expression of interest. For more information click here

Dairy Farmers that are eligible for a type 1 grant, do have a streamlined application for pre-approved items. An assessment is not needed for this grant. Click here for more information.

Focus Farm Open Day (15/10) 
This Tuesday, Neil Gannon’s focus farm is having an open day. Alexis will be there, presenting on water budgeting, irrigation scheduling & making the most out of your water during the dry times.
Changes to Spray and Best Practice Surface Irrigation (BPSI) incentives 
Spray irrigation incentives will now be eligible over areas previously funded for a reuse, but only if the reuse  was completed prior to 1st July 2019.BPSI incentives will now be available for all irrigators including ground water and river diverters within the incentives program area that can source their water through a meter that can deliver accurate and stable flow rates. The meter must be approved by SRW. For more information, please give us a call on 5147 0880.

 ETo – Last Week Totals


Location ETo mm Effective rain* mm (R) Dairy pasture coefficient Required irrigation mm
 (ETₒ – R)
Tinamba 19.6 0.8 1 18.8
East Sale 24.1 0 1 24.1
Boisdale 23.5 0 1 23.5
Denison 21.5 0 1 21.5
Cowarr 20.9 0 1 20.9
Bairnsdale** 25.2 0 1 25.2

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 3.1 mm/day.
The approximate MID flood irrigation interval based on last week’s daily pasture water use rate was 11 days. (This figure assumes that 30 mm of readily available water is held in the pasture root zone divided by the 3.1 mm/day = 9 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 22 mm of irrigation water for the week to meet pasture water use (3.1 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 Wednesday 2nd to 9th October

The predicted weekly pasture water use for the Macalister Irrigation District is 25 mm per hectare (0.25 ML/ha), or a pasture water use rate of 3.5 mm/day.



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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