Making every irrigation count this season
By Robyn McLean, GippsDairy
A late start to your irrigation season this spring could cost you grass production and take a long time to recover. Research has found that the timing of the first irrigation in the season is critical, based on soil moisture monitoring.
Research shows delaying irrigation startup or subsequent irrigations is likely to have an impact on the amount of pasture grown for the season. A seven-day delay in starting up irrigation can result in a 50 per cent reduction in pasture growth for a period of 30 or more days and for every one day delay in irrigation start-up there is a potential reduction in pasture production of about 105 kg DM/ha. A five-day delay over an irrigated area of 50 ha can result in a reduction of about 26 t DM utilisation across the irrigated area.
Delays to your first irrigation can be overcome by carrying out early repairs and maintenance. Be ready to start irrigating by getting on to your maintenance now.
For spray irrigators check:
- Pump pressure, inlet pressure and system pressure are still operating as designed. If the system is running at too high/low pressure it could affect the amount of water applied or be costing you extra for energy you do not need.
- Nozzles. Turn the machine on and check to see if nozzles are working or if there are any leaks. Even with a filter, nozzles can often be
blocked or not spin correctly. The bearings in the spinners can wear out and may need to be replaced.
- Tyre pressures; this is critical to minimising wheel tracking issues. Check your tyre pressures match what is recommended; this is generally around 15 psi.
- Clean out/replace filters.
- Service motors; changing oil and filters.
- Take a reading of your meter now so you can measure your performance over the irrigation season.
- Put out a catch can or rain gauge and see if your system is applying as much you expect – most systems are applying more or less than the machine specifies.
- If wheel tracking was an issue last season – now is a good time as any to fix it. Fill in bad holes, consider changing spray nozzles near wheels over to half sprays or boom back sprays.
Flood irrigation maintenance:
- Spray out channels and drains now. Channels filled with weeds can reduce the channel’s/drain’s ability to move water by 50 percent. If your channel has a 10 ML/day flow rate but is full of weeds then it will only deliver 5 ML/day through your outlet. Clean out your drains to ensure that water is moved off your bays quickly.
- If your bays are flat and water does not run off quickly, think about adding spinner cuts to move the water faster.
- Check your reuse systems pumps/motors and service them as required.
- Check your automation, change batteries and spray equipment to minimise ants damaging your electronics. Wipe over any solar power panels to ensure they continue to charge your batteries.
- Check your bay outlets, fix leaks and ensure they can close.
If you would like to learn more about how to schedule your irrigations this season, or sign up for the weekly Agriculture Victoria evapotranspiration emails, contact Billy Marshall – Agriculture Victoria, Irrigation Extension Officer, Maffra on 0418 718 527 or firstname.lastname@example.org