From corporate office to centre pivots

Tasmania is known for its rich history in taking advantage of cutting edge techniques in water application, from hydro power to irrigation. 

Even today, finding the best way to utilise water is a key aspect of Australian dairy farming. Research into irrigation is a significant avenue of Dairy Australia’s innovation funding, through the Smarter Irrigation for Profit phase 2 (SIP2) program. 

Working within this program is Tasmanian Institute of Agriculture PhD student Tony Kerstan, whose research into irrigation techniques and optimisation is his way of ‘giving something back to dairy farmers’. Tony traded in a corporate career with Hydro Tasmania to study in the open pastures of Tasmanian dairy farms to give back to the industry that gives so much.

Tony’s research is funded by the Department of Agriculture water and the Environment (DAWE), the Tasmanian Institute of Agriculture, and Dairy Australia.

“I grew up on a dairy farm many years ago, but never had the opportunity before to go back to the land. This had stayed in the back of my mind while I was in the corporate world and motivated me to pursue my PhD. I wanted to give something back to my roots - the dairy farmers who work hard in a challenging environment,” Tony said. “I’d like to make their lives easier when it comes to irrigation, especially those using centre pivots, and help them get the best return on investment while protecting soil as a resource.”

Tony’s research is performed across a variety of dairy farm conditions. “We’re looking at four farms, each representing different soil types, rainfall and grazing operations, as well as different pivot sizes,” he said. The farms are located in Tunbridge, a very dry area, Cressy, Meander, and Sisters Creek, all located in Tasmania. For each farm Tony conducts three days of field work, collecting data from the soil. “We’re using innovative tools and techniques to collect the data – such as our own runoff flumes that we’ve produced,” Tony said.”

Effectiveness and efficiency the key to research

Tony has centred his research around increasing irrigation efficiency and effectiveness. “I define irrigation efficiency as simply ‘how much irrigation water is going into the soil’, and irrigation effectiveness as ‘how much of that water is actually getting down to the pasture root zone’,” Tony explains. Finding the right balance of the two is key to efficient water usage in irrigation systems. 

“I think most people assume if you put on, say, 15 millimetres of irrigation, that must mean that the water will flow down 15 millimetres evenly – but that’s not how water actually infiltrates into the soil. Water can go straight down through the soil, horizontal to the soil, and even go upwards,” Tony said.
“A key area of my research is looking into the relationship between soil function under a centre pivot irrigation. An example of soil function is how well the water infiltrates into the soil, the soil structure, and soil strength.”

The first goal of the project is to collect a wide variety of new information. “We’re doing a lot of work that hasn’t been done before – we’re exploring what’s happening in the soil under centre pivot irrigation,” Tony said. “I’d like to think this is a world first. We start by collecting a wide array of data to find those key relationships. We then discuss this data with the SIP2 project, which allows us to then focus the research to funnel down to one or two of those key relationships that add value to dairy farm operations.”

Based on his findings, Tony’s keen to find practical applications for his research. “What I’d really like to get out of this research is to develop some infiltration and soil type rules of thumb to be used by dairy farmers, as well as some new, easy to use techniques that dairy farmers or extension services can use to test their soil or irrigation system on farms and provide those farmers some direct feedback on how their system is performing,” Tony said.

“Water can do three things – it can hit the ground and infiltrate into the soil, it can hit the ground and pond in a location and infiltrate later, or hit the ground and start running off, typically into low lying areas where soils get waterlogged. This is one of the more serious concerns dairy farmers have raised – as that can lead to pugging and other issues,” Tony explained. “If we can determine what will happen with runoff at the point of irrigation, we can then develop techniques for dairy farmers to fine tune their centre pivots.”

Utilising cutting edge techniques

An innovative technique Tony has developed for his research is using dyes to visualise water infiltration. 

“I’m using a purpose-built dye tracer technique which provides quite striking images of how the water is moving through the soil. I haven’t seen it employed anywhere else in the world, so I think I’m leading the charge. It visualises the movement of water throughout the soil – I apply the dye and then dig to several different depths within the soil to see how the water travels and infiltrates,” Tony said. “In highly compacted soils, water travels preferentially via natural cracks, animal holes, and the images provide farmers useful information on the effectiveness of their irrigation.”

“When you look down on the view – you can see how far the dye, and therefore the water, spreads across a pasture. The way soil works is that water doesn’t always travel down in a vertical line – it spreads outwards. Ensuring we know how this works depending on different soils and irrigation use is important to know where and why soil moisture might not get to certain depths,” Tony said.

It's a great tool to help farmers visualise what’s happening under the soil, rather than just a set of numbers or graphs.

“I’ve shown these dye diagrams to farmers and they were quite surprised – the assumption is if you apply irrigation to a certain depth, the water will go down to that depth, but it’s not often the actual case. The dyes are a very simple way of visualising how complex irrigation can be – it’s a lot more than going to the control panel of your pivot and applying a depth and walking away. It’s good for farmers that are irrigating above the evapotranspiration threshold,” Tony said. 

Tony’s goal is to synthesise his findings into techniques and tools for dairy farmers to aid their irrigation management, as farmers don’t always have the time necessary to implement some of the more complex systems to optimise water use.

“I want a farmer to be able to look at their soil type or irrigation issues and be able to easily find what to do to get some quick wins. Even if it’s not the entire answer for them, it’s a start. Getting them 80% of the way there in a simple and easy to understand way would be a great outcome for my research,” Tony said.

Find out more about the irrigation research Dairy Australia is investing in at Smarter Irrigation for Profit.