Management

Agriculture Victoria provides irrigation tips as warmer months approach

By Rodney Woods

This winter we have been lucky enough to receive more rainfall than last year.

Now as we move into spring and temperatures start to rise, the evaporation rate will increase, as will the requirement for irrigation.

Below are some general suggestions to follow, to help you prepare for the approaching irrigation season.

These actions will maximise the opportunity for pasture growth and reduce the chance of breakdowns during the season.

Surface irrigation

Farmers with surface irrigation systems can take several steps on farm to ensure their systems are working efficiently.

The first and most important step is to remove vegetation, silt or other blockages from channels and drains to make sure irrigation water flows well, with minimum head loss.

Anything in your channels or drains that slows down the flow of water will cause head loss and increase the chance of waterlogging or losing water to deep drainage, depending on your soil type.

Heavier soils will show waterlogging issues, such as reduced pasture growth and quality, while lighter soils will lose a lot of water to deep drainage.
Ensuring water flows on and off the bay as fast as possible is key to efficient surface irrigation.

Another important step is to check your outlets for any damage during the off-season and repair any outlets that have leaks or other issues.
The last thing on your list is to check your reuse pump is running efficiently and has been serviced and maintained.

Centre pivots and linear moves

If you are an irrigator with centre pivot and linear move systems, the first step is to check your sprinkler chart and ensure the sprinkler package matches the chart and your machine.

It is recommended that sprinkler and regulator packages should be replaced every 10,000 hours, at a minimum.

Sprinklers account for over 70 per cent of your system’s performance, therefore it is vital to get this part of your machine right.

While you are there, turn the machine on and inspect your machine for any broken or leaking sprinklers. Ensure your end gun and booster pump, if you have one, turns on and off in the correct places.

At this stage, checking the pressure at the pump supplying the system is also important, to ensure the entire machine can run and maintain the correct pressure.

Running higher pressures than required will waste energy and cost money, while lower pressure than recommended will decrease the uniformity of the system.

While the machine is running, measuring the system water pressure with an accurate pressure gauge is important.

Measurements at the second span, middle span, and last sprinkler will ensure the system is running at the correct pressure to supply the spans and the end gun or will highlight pressure problems that need addressing.

A useful tip is to also check your irrigator’s tyre pressures; if they are too highly inflated this can exacerbate wheel tracking, whereas too low pressure can increase resistance and in extreme cases the tyre can come off the rim.

The last thing on your list is to check your pump is running efficiently and has received appropriate servicing and maintenance.

If you are pumping from a river or on-farm storage that contains solid trash such as sticks, leaves, or large amounts of sediment, consider a screen on the suction to decrease the amount of litter entering the pivot and potentially blocking the sprinklers.

Fixed sprays/bike shift laterals

Irrigators with fixed or lateral sprays need to ensure that their pumps are operational and supplying the correct pressure for their spray systems.

Running higher pressure than required will waste energy and cost money, while lower pressure than recommended will decrease the uniformity of the system.

Regular maintenance and servicing of pumps can more than pay for itself when ensuring correct functioning and problem prevention.

The next step is to check all visible infrastructure (lines, hydrants, posts, sprinklers) for damage/leaks, and unblock any sprinklers that are clogged.
Hopefully these few tips can help you make the most of your irrigation system and season.

A well-functioning system and correct scheduling of irrigations will set you up to grow the most pasture you can in the most efficient way.

For more information on irrigation scheduling, visit: https://extensionaus.com.au/irrigatingag/home or call 136 186.

By Agriculture Victoria irrigation extension officer Alexis Killoran