Biological soil crusts (BSCs) have been known for centuries—botanists have noted how a wide variety of organisms—bacteria, fungi, lichens and others—can colonize areas of open and arid soil. However, it has only been since the 1970s that they’ve been studied seriously, when agronomists and soil scientists began to study how these ecological units played an important, functional role in the transformation of deserts into areas of flourishing plants. These crusts create a “living skin” which prevents sand particles from blowing away.
The Chinese Academy of Sciences has been conducting experiments for several years in northwest China using lab-grown cyanobacteria in plots near the Taklamakan Desert in Xinjiang to transform the desert into an area well-suited for plants to take hold, since the BSC captures nutrients and retains water within the first inch or so of soil.
Cyanobacteria are bacteria that use photosynthesis and are the first organism to produce oxygen; they’ve been on Earth for at least 3.5 billion years. The development of BSCs in the wild can take decades, but these experiments show the formation of the crust to develop in as little as 10 months. The experiments and their results were originally published in 2020 in the online journal, Soil Biology and Biochemistry and in 2024 in Geoderma.
“Under a microscope, biological soil crusts, thin living layers on soil surfaces, show a mesh of bacterial threads wrapped around sand grains,” explains Earth.com.
“To hold that mesh together, cells ooze sticky sugars between grains, and those sugars harden into a thin, cohesive layer.
“The crust acts like glue by holding sand grains together and helping prevent invasive plants from taking root. Footsteps, tires, and hard raking can break the surface, so building crusts at scale also needs long-term protection.”
Further research and long-term monitoring will be required to determine how this process could be scaled up for large-scale greening of the deserts.
