Almost 50 percent of Center Pivot irrigation systems in New Zealand are over 10 years old. This means they are now beyond half their serviceable life and issues will be starting to occur.

There are also many Center Pivot systems that have been installed on rolling hill country, or that climb up and down river terraces. This places increased wear and tear on componentry resulting in a much shorter serviceable life.

Many pivots have had additions to them like under-slung effluent systems. If these are not regularly flushed and maintained, they place extra stress and wear on the pivot structure, including corrosion from the build up of solids.

The Canterbury 2013 windstorm resulted in many components being re-used to get systems up and running running quickly. This has resulted in a wide range of componentry age within some pivot systems.

Given all the scenarios above, it means most irrigated farms in Canterbury are getting to a stage where they need a skilled eye run over their irrigation equipment at a minimum of 3-yearly intervals. This will help avoid costly mid-season breakdowns as well as establish an accurate 5-year capital expenditure (re-investment) plan – both of which are sensible for your business.

Water Strategies has been recently undertaking much infrastructure assessment work for clients, providing each with a detailed report on the remaining serviceable life alongside an associated 5-year capital expenditure plan. The following are the key points we’ve noted from the center pivot infrastructure assessments we’ve undertaken:

Centre Point: Look for loose bolts and cracking. If cracking is observed this is a big red flag as it almost certainly means there’s something seriously wrong and the pivot structure could be starting to fail. The other key consideration for the centre tower is to ensure the pivot point is well greased.

Towers: Again look for loose bolts and cracking. Gearboxes and motors should be serviced annually and in Canterbury their serviceable life is typically 10 years, but if you have wheel rut issues this will become much much shorter.

Truss Rods: These are an important component as they provide stability to each spans structure – the span pipe and truss rods should form a well balanced triangle. Undulating ground places a high degree of pressure on truss rods. Of the pivot spans we assessed last month we found over 40{d63bd7a1bfb28fa6de66fde08e78ca1ad36bbb55755b6aa7dcff30a97ce0b189} of them had stretched, which resulted in the span structure being unbalanced and at risk of failing (collapsing).

‘Unbalanced pivot span with stretched truss rods and bent spreader bars’

Span Pipes and Goose Necks: Corrosion is the primary issue with these and it takes a keen eye to know what to look for as they rust from the inside out!

Endguns: Endgun booster pumps are often overlooked and commonly fail due to the rain cap corroding which allows water to enter into the pump bearings. Endgun sector stops should be regularly checked to avoid over-watering occurring in the overhang zone. The endgun controls also need checking to prevent off target irrigation, particularly if you’re beside a road.

There’s much to consider when assessing the condition of your center pivot, so if you’ve any questions the knowledgeable team at Water Strategies is always keen to help.


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