As drought conditions become more frequent and prolonged, engineers are increasingly focused on how water moves through soil rather than solely on how much water is applied. At Texas A&M University, a research group led by Dr. Mustafa Akbulut, professor in the Artie McFerrin Department of Chemical Engineering, has developed and tested a soil modification strategy designed to slow water loss below plant roots. The work examines whether a thin layer of chemically modified sand can improve water retention and support plant growth under water-limited conditions.
Arcot, Y., Srinivas, R., Mu, M., Maghoumi, M., Cisneros-Zevallos, L., & Akbulut, M. E. S. (2025). Organosilanized Hydrophobic Sand for Drought Resilience: Reducing Water Percolation and Enhancing Crop Growth Conditions. ACS Omega, 10(33), 37583–37596. https://doi.org/10.1021/acsomega.5c03952
Drought has historically reshaped agricultural systems, sometimes with lasting social and economic consequences. Today, rising temperatures and changing precipitation patterns are increasing evaporative losses from soil, particularly in regions dominated by sandy or highly porous soils. In these environments, irrigation water often drains beyond the root zone before plants can fully use it, placing additional strain on already limited water supplies.
Texas A&M University, a research group led by Dr. Mustafa Akbulut stated,
“We only changed the surface chemistry of sand by using an extremely tiny layer, less than two nanometers. For context, our hair is around 10 micrometers, so a thousand times thinner than our hair.”
Rather than adjusting irrigation methods, the Texas A&M researchers focused on altering the physical behavior of sand itself. Sand is primarily composed of silica, whose surface contains hydroxyl groups that readily interact with water. These interactions contribute to rapid downward water movement. By chemically binding these surface groups with organosilane compounds, the researchers created a hydrophobic coating on individual sand particles.
The modification occurs at the nanometer scale. The hydrophobic layer is less than two nanometers thick, leaving the bulk structure of the sand unchanged. While the sand remains mechanically identical to untreated material, its surface no longer attracts water in the same way. This change alters how water moves through the soil profile without introducing absorbent materials or polymer-based additives.
To test the concept, the team conducted controlled growth experiments using tomato plants. Soil columns were prepared with standard topsoil above a sand layer. In selected samples, a layer of hydrophobic sand was placed below the root zone. All samples received the same amount of irrigation, and the water that drained through the soil was collected and measured over time.
The results showed that soil systems containing the hydrophobic sand layer allowed less irrigation water to drain away. Plants grown above the modified sand consistently showed greater growth compared to those grown in unmodified soil. The findings suggest a direct relationship between reduced water percolation and improved water availability for plants.
According to Dr. Akbulut, the placement of the hydrophobic layer is central to the approach. By positioning it just below the root zone, the system slows water loss without directly altering the chemistry of the soil where roots actively grow. The researchers envision that, in practical applications, the material could be injected as a thin subsurface layer several inches below ground level.
Unlike some soil conditioners that swell, degrade, or interact with nutrients, the modified sand is chemically stable. Its function is passive, requiring no external energy input or ongoing maintenance once installed. This characteristic aligns with engineering strategies that emphasize long-term resilience through material design rather than operational complexity.
The technique is particularly relevant for sandy soils, which are widespread in agricultural regions across the southern United States and other arid and semi-arid parts of the world. These soils typically require frequent irrigation due to low water-holding capacity. Improving their ability to retain moisture could reduce irrigation demand and improve crop stability during dry periods.
While the experimental results are promising, the researchers note that additional work is needed before field deployment. Long-term durability, environmental impact, scalability, and economic feasibility will need to be evaluated under real agricultural conditions. Future studies may also explore how the modified sand performs with different crops and soil types.
The research contributes to a broader effort in agricultural and environmental engineering to manage water more efficiently by controlling its movement through natural systems. As climate variability continues to challenge existing practices, approaches that rely on subtle material-level changes may play an increasing role in sustaining food production with limited water resources.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
