Different farmers have different needs: customising reclaimed water for agricultural use

Better understanding the needs and cost pressures of farmers could help water utilities increase agribusinesses’ use of reclaimed water, according to new research from SA Water and the University of South Australia.

Since not all agriculture has the same needs, by examining water-use data for almond orchards, vineyards, glasshouse tomatoes and lettuce, the researchers were able to better understand the influences shaping water use for different types of crop production.

SA Water Lead Wastewater Scientist Ben van den Akker said that SA Water aims to maximise water reuse to boost economic opportunities in South Australia.

“That can be achieved, in part, by agriculture — there are a lot of benefits that agriculture gets from access to reclaimed water,” he said.

“So we're looking at how we can encourage uptake to provide these economic opportunities. There are a number of barriers when developing a new water recycling scheme, including the economic viability.”

Looking at demand

University of South Australia Professor of Economics Lin Crase said that the water sector often focused on supply-side issues when it came to cost.

“But as economists, we know that ultimately demand is pretty important as well,” he said.

“Our motivation was around really interrogating water demand to try and better understand how sensitive agricultural enterprises, in particular, are to interruptions to water supply and price.”

University of South Australia Senior Research Fellow Dr Bethany Cooper said the researchers wanted to understand the diverse water treatment requirements of different agricultural ventures.

“It's not one size fits all,” she said.

“Often farm enterprises are considered as one body or one group, so we were interested in understanding the different preferences and different exposures to different risks that different farmers face.”

Acknowledging this would allow utilities like SA Water to better customise their reclaimed water offerings to their customers.

“We can then use that information to try and craft offers that recognise these differences to try and encourage uptake,” van den Akker said.

“This is a first step that identifies that there is heterogeneity, there are differences in production risks — the cost of water can affect some farmers more than others, whereas access to water bears a bigger influence on production risks for some farmers than others. It's about unpacking that and identifying those differences.”

Van den Akker emphasised that reclaimed water does have benefits to offer to farmers.

“They get access to climate-independent water that's nutrient-rich, so they're not so much dependent on rainfall,” he said.  

“But obviously there's a cost attached to that in providing that water, and so this study is to understand the impact that access to water and cost has on the profitability risks.”

Gauging sensitivity

The technique used in the study would also help water suppliers identify which enterprises are particularly sensitive to water access and water prices.

“This can help water providers inform their investment decisions around investing in water recycling treatment plants to help them gauge what the demand might be from their customers for this type of water,” Cooper said.

“It can also help to inform and assist the water provider with targeting strategies to foster higher uptake of reclaimed water.

“For instance, if there are certain farm enterprises that are more exposed to supply interruptions, they're going to stand to benefit more from having access to an uninterruptible water supply.”

That information could also better guide decisions about how much utilities should charge for additional water supplies, as well as the viability of potential infrastructure that isn’t yet built.

“The modelling around a certain farmer’s sensitivity to water prices can help inform the water provider when thinking about investment decisions around building future water supply systems,” Cooper said.

Crase said that although the study focused on only a few crops relevant to South Australian agriculture, the technique could be used more broadly.

“The simulation modelling is what drives the really interesting results, and so it was as much about demonstrating the value of the technique that could be applied to lots of contexts,” he said.

“In fact, the technique is applicable beyond agriculture …  the technique creates simulations, and then we can work out what's the one variable that’s really important.”