Australian study finds way to up value of desalination for farming

Scientists at Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) have found that the addition of nutrients could make desalinated water more financially attractive to farmers.

“Desalinisation technology is considered to be an expensive option,” said CSIRO Land and Water principal research scientist Dr Olga Barron.

“For every crop you might have specific needs for certain minerals and certain fertilisers, so you can introduce [these], and when you use [nutrient-added] water, you actually use less to improve the quality and productivity of agriculture,” she added.

The researchers’ investigation into whether groundwater desalination technologies could generate cost-effective water supplies at agricultural sites across Australia revealed cost to be the main limiting factor in the use of desalination for agriculture. Fewer than 10% of possible sites were found to be likely to be supplied with desalinated water for less than A$1 a kilolitre.

Barron said many farmers currently paid just 20 cents a kilolitre for water, and were unlikely to pay more than $1.20 a kilolitre.

In determining probable costs, the study, funded by Australia’s National Centre for Excellence in Desalinisation, included the distance from agricultural land and towns, the number of bores required at groundwater sites, bore installation and maintenance costs, and the cost of disposing of the by-product brine.

According to Baron, desalinated water needed to improve farming efficiencies, or come with something extra to make it more cost-effective, such as adding and nutrients to improve crop production.

Barron said desalinated water could be conditioned with minerals and nutrients at the same time it is treated. She said the research revealed an opportunity for someone in the agricultural industry to develop infrastructure to support the sale of nutrient-added agricultural water. “[If] you use less water and produce much higher quality agricultural product, it’s actually offsetting the cost of desalinisation,” Barron said.

The study identified groundwater as the most likely feedwater source for cost-effective desalinisation, with the possibility of increasing water production by up to five times if feedwater salinity was only slightly higher than the salinity required for crop use.

The most cost-effective results were found in greenhouse agriculture, where high-value crops are intensively grown.