VRI & Irrigator Maintenance

In some areas it will not be long before pumps start up and irrigators are set in motion. So if you have not already done so you may want to consider a quick irrigator WOF check to make sure you get the best out of this critical piece of farm infrastructure. It may also be worthwhile evaluating if your irrigation system can be optimised or improved to save on costs such as water or energy.

Simple pre-season maintenance checks are able to be done by farm staff. A basic inspection while the irrigator is turned off can help assess if you will require service work to be carried out. It is recommended to park the pivot in an accessible position and ensure that the electrical isolator switch is tagged and locked to prevent accidental starting.

Every centre-pivot should be supplied with an operation manual which can come in handy, for most you will find this in the inside door of the main panel. Some manuals actually include recommended maintenance checks with instructions to show you how to carry them out. Whoever is carrying out the checks needs to be aware that centre-pivots are generally high voltage electrical systems, so leave all electrical checks to a qualified Service Technician. And if there is a need to work at heights make sure you have safe equipment to do so.

A walk up the length of the machine will allow you to assess any damage and parts requiring repair. Tighten, adjust or replace if possible, or note down so you can inform your Irrigation Dealer. Greasing of all the grease nipples as you go is highly recommended, important parts to maintain well-oiled are the pivot point, gear boxes and drive shafts. Checking that all moving parts around tower boxes are free and lubricated will help reduce problems for the upcoming season.

The uniformity of a centre pivot relies heavily on the correct sprinklers being fitted to each dropper, checking that the sprinklers installed match the sprinkler chart will allow your pivot to apply the specified application rates. Armed with a pole of some description you should be able to free any sprinklers that have become tangled over the truss rods.

It pays to check that the tyres are pumped up to their optimum pressure rating. As tyre pressure is critical not only for the life of the tyre, rim and gearboxes, but also the application rate of the sprinklers. Over or under-inflated tyres can apply higher or lower application depths than planned.

Once you have checked everything over with the pivot stationary, providing there are no required repairs, the next step is to run the pivot. This is ideally done when the soil is not too wet so that you don’t create big wheel ruts, or worsen those that need attention. Wheel ruts significantly increase the load and wear on the drive train so should be dealt with when possible. GrowSmart Precision VRI technology can be used to reduce the spray onto the wheel tracks to help minimise wheel rutting.

Obvious checks while running the pivot are leaks. Some of these can be fixed with simple repairs such as replacing droppers, but others may require a call to your Irrigation Dealer to sort out. While walking the length of the irrigator listen for excessive vibration or noise that may indicate issues on the towers motors, gear boxes and drive shafts.

Some component wear will depend on water quality as high concentrations of iron, suspended solids and effluent solids or grit can increase damage and degradation to parts. A general check is recommended every season to ensure that worn sprinklers and pressure regulators are replaced to maximise the efficiency of the pivot. Common causes to check for are blockages or damages from knocks during the previous season, missing sprinklers and spray plates.

At the end of the irrigator remove the sand trap cap (with the irrigator turned off) and flush the system to get rid of any sediment build up, this is very often common in the overhang. If your water supply has a high level of sediment than it is recommended that this is done regularly.

Reducing the risk of breakdowns during the irrigation season will help avoid production loses due to downtime for repairs. Long term water and energy cost savings are also possible through the installation of technology such as variable rate irrigation, which can reduce nutrient leaching as well. If you would like more information on recommended maintenance checks for your irrigator, system calibrations or technology to improve water use efficiency call your local GrowSmart by Lindsay Dealer. 

Regular Farm Irrigation Assessments Pay-Off

The current soil moisture deficit conditions in many areas of New Zealand should prompt irrigators to assess the efficiency of their irrigation system and management practices. The information that this blog is beginning to build upon hopes to increase understanding and awareness of technologies so these improvements can be implemented.

What is yet to be defined is Irrigation System Efficiency, while you will find many variations in the wording of definitions in a nut-shell it is the ration of irrigation water available for plant growth to the total amount of irrigation water delivered to the farm. So 80% Irrigation System Efficiency means that 80% of the water delivered to the farm has been applied and stored in the crop root zone and therefore available for plant growth.

Recent roadside assessments of irrigation systems show there are some very simple irrigation management modifications that can be made with only the basic level of knowledge.

Irrigating the road = 0% irrigation efficiency as well as being a safety hazard. However much irrigation you put on the road it’s still not going to grow grass!

If your irrigator has an end gun control function then contact your irrigation dealer to find out how to program the end-gun to turn off at any point it is irrigating outside the boundary of the growing area. If your irrigator does not have an end-gun control function than you may consider a GPS End Gun Controller, for more info click here or contact your local Zimmatic Dealer.

Ensuring that the staff that are charged with managing your irrigation as well as those that occasionally help out are adequately trained is really important. If there is not the time or resources to carry out the training in-house there are courses run through IrrigationNZ and many online resources that are very helpful. Considering a guidance system for shifting K-line’s could resolve many issues and result in a significant increase in your irrigation efficiency.

Regular maintenance of your irrigation system can save wasted water as well as forgone growth from under-watering. As an example a blocked sprinkler near the end of a 500m centre-pivot could be causing ~5ha of your property to be under-watered. Many of these maintenance issues are easily identified provided staff are aware of what to look out for.

Limitations of irrigation infrastructure can be a constraint to improving your irrigation efficiency. As seen in the image above the irrigation water being applied within the ditch is not contributing to pasture growth, and is likely to cause wheel rutting and potentially a stuck pivot. Should your centre-pivot or linear-move irrigator run over non-productive areas, roads, tracks or water-ways then variable rate irrigation technology would allow you to avoid irrigating these areas. This not only will save you water and potentially energy costs but also prevent the other issues that arise.

Future blog posts will discuss variable rate irrigation technology in more detail and the many applications in addition to avoiding irrigating certain areas where the technology offers benefits.