Getting deeper into irrigation

By Tony Benny

New technology developed by NIWA will help farmers who irrigate their farms manage their system more efficiently.

Farmers trying to make strategic irrigation decisions that take into account climate change and environmental regulation now have a new online tool that brings together data around water supply and potential restrictions as well as NIWA climate change projections to help them crunch the numbers.

IrriSET is just one output developed following a research project, Irrigation Insight, where NIWA scientists worked with farmers in North Canterbury to plan how best to use irrigation water from the Cust River, using soil moisture data, weather forecasts and supply information.

Perrin Ag principal consultant Carla Muller previously worked for NIWA and spent three years on the project before joining Perrin Ag, which is now keen to see the tool used by farmers.

“We worked with a group of farmers down there and actually sat round the kitchen table with them and asked, ‘What are the questions you have around irrigation and how do we then solve them?’” Muller says.

“The whole project was set up from a co-design perspective.”

For the farmers, the research project has led to much more efficient use of irrigation water, and now other farmers and growers can harness a tool developed as part of the project to help future-proof their irrigation systems.

It’s likely to be most used in Canterbury, where there is more irrigation than in the rest of New Zealand, but it will work in any region.

“With the IrriSET tool you can link in your existing and future supply constraints and then you can overlay current and future climate, irrigation infrastructure limitations and then consider what your irrigation system could look like now and what may be needed into the future.”

The tool is freely available on NIWA’s website and essentially all farmers have to do is fill in the boxes, and IrriSET produces a report.

“It’s a tool we envisage farmers using when they have a big decision to make, ‘Should I build a storage pond, should change to a pivot, should I buy the neighbours’, have I got enough water to do that?’ – that kind of strategiclevel planning decision.”

The tool has detailed climate changed projections and implications built in, at a level not easily available to farmers otherwise.

“You might be able to look up the climate change maps, but actually being able to access a tool like this that has NIWA climate change data built in gives you a way to turn data into information. You can actually put in your farm location and see what it does for your farm.”

It is simple to use, but Muller says it is likely farmers will use it alongside a consultant or perhaps a bank manager, to take into account other factors influencing their decision.

“Can I get the capital to fund irrigation, what do I do with additional, or less, grass? Those are decisions that require farm systems expertise as well.”

Part of the original research project was looking at the economic impacts of irrigation, trying to answer basic questions like, “If I put on 20mm, what does that actually cost me?”

“We did a lot of work around trying to understand that cost of irrigation application, as well as the benefit of that in terms of growing grass. We then balanced the desire for pasture and the cost of irrigating with potential environmental implications such as drainage”

IrriSET answers those questions under current conditions but can also look into potential future climates, so farmers and growers can take steps to future-proof their businesses.

“We’ve got irrigation schemes that are changing, we’ve got weather that’s changing, rules that are changing, all of that – it is important for farmers to consider what their business needs in terms of infrastructure investment now and for the future.”

The online tool has already proved its worth on farm, says Muller.

“An earlier version of the tool helped an arable farmer irrigate more land with the same amount of water.

“We have also used it on a sheep and beef farm looking at new irrigation on their flat land. We worked with them to understand the implications of that under climate change and what they would do with the additional feed grown.

“In the end they decided it wasn’t worth it unless they could put a higher value crop in. Now they are looking at diversifying a small part of their business to an alternative land use with the support of irrigation. So there’s some cool stuff coming out of it.” n