Blooming the deserts

Could a limitless water supply be within reach?

Israeli scientists are at the cutting edge of research into the use of saltwater and waste water in agriculture. Their work could prove very significant in a world where water is an increasingly precious resource.

Due to its geographical position and arid climate, Israel has since its foundation in 1948 put irrigation at the heart of its approach to agriculture. Being able to ‘make the desert bloom’, growing crops where there was nothing but barren ground, is central to the country’s self-image. Treating salt water and reusing water for irrigation have played a crucial role. Currently, 85% of the waste water in Israel is treated and recycled, and 50% of the water allocated to agriculture is obtained from treated waste water.

Sampling in a wastewater effluent reservoir used for irrigation (Image: E. Cytryn/Volcani Center)

Water and climate change

It’s a track record that is now globally relevant thanks to climate change and water shortages. It would make a huge difference to food security if we knew we could access a never-ending supply of good quality water. As Eddie Cytryn, a researcher at the government-funded Volcani Agriculture Institute puts it: “Israel is a pretty good model if we talk about a growing world population, climate change and water scarcity. You have to basically feed more people: you’re going to have more and more land that’s going to need to be irrigated.”

The general idea when it comes to using saltwater and waste water is simple: it involves using these readily available sources of water rather than relying on a fresh water supply. Of course, the reality is more complex. The water content has to be carefully monitored – levels of salt can have a major effect on soils and yields.

It’s also important to understand how plants and soils respond to different types of water. Then there is the problem of treating waste water to make it usable and avoid potentially causing public health issues (for instance by facilitating the spread of microbes responsible for diseases or allowing antibiotic-resistant genes to enter the food chain).

“Israel is a pretty good model if we talk about water scarcity”

- Eddie Cytryn, researcher, Volcani Agriculture Institute

Low-tech can be best

Scientists are looking at the question from a holistic, environmental perspective which offers the promise of solutions that could be shared internationally at little expense. This involves working with nature rather than trying to control it and looking more closely for instance at how soils work. As Cytryn puts it: “Because soil contains a diverse array of micro-organisms it can do many different things. If the ecology of the soil is right, we can actually create an environment that’s very competitive, where intruders will have a very hard time persisting. It’s an old-fashioned but potentially effective method for treating or polishing treated wastewater. Nonetheless, this practice should be monitored carefully to assess the long-term effects on soil quality.”

An avocado grove irrigated in parallel with either freshwater or treated wastewater (Image: K. Narkis/Volcani Center)

Reducing wastage

Cytryn’s colleague at the Volcani Center, Shmuel Assouline, for his part, highlights the role that better understanding of plants’ interactions with their environments could play: “We are trying to understand the relationship between microbial activity and the root system so that we can also improve the crop response to the environment. “ Assouline adds that work is ongoing to more closely align the supply of water to the requirements of crops, thus reducing wastage.

Huge potential

There are still quite fundamental challenges to overcome to reach the ideal of a limitless water supply. The Israeli example does show that it is at least possible to take substantial steps in that direction. The approaches developed in the Middle East are already being shared elsewhere. Israeli government officials signed an agreement in 2017 with their Indian counterparts on water conservation and recycling. The potential global impact of these technologies is therefore huge.