Agriculture in the United Arab Emirates faces serious challenges. Most of the country is desert, and only about 5% of its land is suitable for farming. This means the UAE can produce only 10% to 15% of its food and relies heavily on imports. Nor is this a distant, localized issue: more territories around the world are becoming desert-like.
It doesn't rain much in the UAE, to say the least, and even with irrigation, growing crops in sand is a huge challenge. Sand doesn't contain many nutrients, and its grains don't stick together like particles in fertile soil do. That's why sandy soil is so prone to erosion: it can't hold water for long, letting it quickly seep through the gaps between the grains.
Researchers at Switzerland's Empa institute and Khalifa University in Abu Dhabi took on the challenge of making sand more suitable for growing crops. They call their technology "living sand," and the idea behind it is clever and simple: if things don't stick, add something sticky. The researchers introduced specific bacteria and fungi to the sand to help hold it together. These microorganisms produce a whole network of fibers and biopolymers that spread between the sand particles and make them more cohesive, much like mixing sand with a natural glue.
To test the technology, the scientists used both laboratory sand and sand collected from dunes in Abu Dhabi. The resulting material was significantly more stable than pure sand, and the bacterial treatment reduced the rate of water movement by a factor of six. The microorganisms also need nutrients to grow and spread, but that part seems to have an easy solution. According to the researchers, sugars from organic waste could be a potential source, so the "food" for the bacteria is already widely available.
The researchers also tried another method. They used bacteria that produce nanocellulose to form so-called geotextiles, which are very thin cellulose sheets combined with sand to form layers. This layered structure makes the sand more stable and helps it retain water. The results were even more impressive this time: water seeped through at one twenty-eighth of the rate observed in pure sand. The most obvious drawback, for now, is how time-consuming this method is.
None of these technologies magically turn sand into highly fertile soil or demonstrate that crops actually grow in it, at least not at this stage of the study. Even the treated sand is still not as strong and stable as actual soil, but that wasn't the goal. The idea is to give the sand just enough cohesion and water-holding capacity to create conditions in which plants could potentially grow. So this study is a first step rather than a complete solution, but it's already a big one.
"This approach allows us to introduce organic matter and water into the sand and stabilize it somewhat. Ideally, this will then enable the growth of further microorganisms and plants, thereby initiating the process of making the soil more resilient and fertile," says Gustav Nyström, head of Empa's Cellulose and Wood Materials laboratory and one of the authors of the study.
The work is still at the laboratory stage, so the next step will be to test whether the sand treated with bacteria and fungi can support plant growth in greenhouse and field environments.