Farm advice: Efficient irrigation systems and winter maintenance

By: Stephen McNally, IrrigationNZ principal technical advisor

IrrigationNZ offers some pointers around efficient irrigation systems and winter maintenance


It’s hard to believe that many Cantabrians were irrigating well into autumn to then turn around to see some of the underwater come end of May after an incredibly high rainfall event. Our thoughts are with those who will face ongoing clean-up and infrastructure damage – it will sure be a weather event for the record books. However, in the broader view of climate change impacting our sector, this highlights the impact of extremes of dry and wet.

In anticipation of continued climate change with extreme events placing demands on soil moisture management, we must keep our eye on water resource efficiency and how that helps us meet our business, environmental, and community expectations. 

One way to ensure water for irrigation is being used as efficiently as possible is through understanding your systems in detail and ensure maintenance is up to date. With many irrigators parked up for the off-season, now is a great time to plan for ensuring your systems are running properly and are ready for next season; this year is flying by, and September will be here before we know it. 

Your aim as an irrigator is to use just enough water applied through your equipment to keep the soil at its best moisture content down through the depth of the root zone. Make sure you understand what that rooting depth is and how the soil changes down the profile. Think of it like a sponge or even a stack of different sorts of sponges that each have a different ability to hold plant available water but only to a point. 

The result of too much water applied to saturated soil means it simply flows out the bottom of the root zone and its effectiveness will be lost, along with the time, energy, and money you used to get it to the paddock. Or if the soil is too wet, the water may not even penetrate and flow across the surface or pond. A saturated soil where all the large pore spaces are overfilled with water prevents oxygen from getting to the actively growing and respiring root tips where most of the water and nutrient update is occurring. 

The linkage between what water you can extract under your consent and the water that’s needed in the soil root zone is your irrigation equipment – the pumps, filters, pipes, and emitters, whether those are pivot irrigators or under tree sprinklers. Each part of this equipment’s pathway from source to the soil presents opportunities for precision and efficiency. If it’s not designed, installed, and operated by suitably qualified and accredited practitioners to the best available practice standards, you risk not gaining the most from the water, energy labour, and money committed to it. Having intimate knowledge of the way your system operates gives you the confidence to make good decisions on water use, minimising volumes extracted, and improving plant growth. Of all the aspects that can affect your system precision, uniformity of application is one of the most significant and it’s relatively easy to have tested. 

The Bucket Test app that incorporates a simple process of capturing water underneath your irrigation system gives you a quick indication of the uniformity of distribution. If the distribution pattern across the system is poor, you’re likely overwatering some parts of the soil profile, with a risk of leaching nutrients and underwatering others leading to low growth areas.

There’s plenty of clever technology appearing in the market that can measure and monitor many parts of your irrigation processes, including your water take volumes, power consumption, soil moisture levels, and services that look at weather patterns in your district, but be prepared to adjust your thinking. What you may have been confident of through intuition may not be quite as you thought, especially as you gain an understanding of the data and analysis relating to soil moisture through the root profile. Give technology time. You will need to understand how it reacts to different situations for you to build trust in what it’s indicating to you; you’ll see it as another tool you can use to optimise your business of farming and growing.

Train yourself and your staff, attend courses, get some qualifications under your belt, and look to gather knowledge from the experts available to you. And then share your experiences so others can see the benefit of that process to their own situation but always be aware that each operation is unique to the location, the soils and weather patterns, and how each operator wants to farm the land.   

IrrigationNZ is a national membership organisation that looks after the interests of irrigating farmers, growers, and the industry professionals that service them. We actively engage with our members and other stakeholders in the delivery of irrigation best practices and helping shape policy. We facilitate the adoption of best practices in irrigation and water management through a world-class resource base of knowledge and effective communication.

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