Sand-based aquaponics system offers more affordable path for farming in water‑scarce regions

How do you solve the growing gap between agricultural demand and decreasing land availability? According to new research from the College of Agriculture and Life Sciences, you farm in something that is inexpensive, plentiful, and everywhere on Earth: sand. 

Researchers are working on improvements to sustainable agriculture that could reduce environmental damage, lower production costs, and expand food growing opportunities in water-limited regions. The system they’re using, referred to as the Integrated Aqua-Vegeculture System (iAVs) and first developed by researchers at North Caroline State University in the '80s, reimagined aquaponics by replacing separate filtration equipment with one of the world’s most abundant natural materials, by transforming sand into both a planting medium and a biological and mechanical filter. 

Addressing agriculture’s core constraints 

Global food demand is increasing rapidly, with the U.S. Department of Agriculture expecting it to grow 70 to 100 percent by 2050. As the population grows, farmable land dwindles, and many regions face risk due to water scarcity. In addition, increased demand increases nutrient runoff from farms, which often flows into rivers and lakes, leading to the over-enrichment of water and causing harmful algal blooms. 

“It can destroy aquatic life,” said Buddhika Abeyrathne, a Ph.D. student and project lead in the Department of Biological Systems Engineering. “So, we designed a project building on the work of Mark McMurtry and his team at NCSU to see if the efficiency of these systems can be increased." 

Aquaponics already offers part of the solution by pairing fish production with hydroponic plant growth. Fish waste provides nitrogen and phosphorus for plants, while plants help clean the water. However, traditional setups can be expensive for growers. 

Why sand?

iAVs aims to simplify and democratize the aquaponics model. With sand as an easy-to-use source, the cost would be low compared to conventional applications. But sand alone is not an ideal growing medium.

“Sand has very low cation exchange capacity,” Abeyrathne said. “It cannot retain many nutrients and has a lack of water retention, which would cause issues for growing.”

The team’s innovation lies in treating sand not only as a planting medium and mechanical filter, but also as an active microbial habitat within the system. As nutrient-rich water from the fish tank flows through the sand beds, organic matter accumulates and microbial activity increases. This activity converts ammonia from fish waste into nitrate.  

By profiling microbial communities across different sand types and depths, this study aims to identify how microbial structure and function contribute to nutrient cycling, organic matter retention, and overall system performance.

“The nutrients and the solid waste filter out and provide organic matter into the sand,” Abeyrathne said. “When we increase the soil organic matter, we see increased activity, which then benefits the growing process.”

The concept for the project was initially conceived by undergraduate students in the on-campus Innovative Agriculture Club; they also single-handedly built the pilot system.

Currently, the team — which includes undergraduate researchers in the College of Engineering — are testing the system on a small pilot scale. They are also evaluating different sand types to understand how each affects filtration and nutrient cycling. Once the data is analyzed, they expect to determine how the system can be scaled up. 

“We want to eventually get this to a greenhouse concept to start,” Abeyrathne said, noting that aquaponics relies on controlled environments. “But I think we can successfully implement it in a large-scale production system too.”

Most crops tested so far are leafy greens, which thrive in the upper, organic-rich layer of sand. Early studies have also explored crops like tomatoes and cucumbers, and the team hopes to expand testing to additional species.

A closed loop system with broad benefits

Similar to other aquaponics models, iAVs is a closed-loop, nutrient recycling system that conserves water and reduces environmental contamination. 

“My major concern is reducing nutrient outflows from agricultural lands,” Abeyrathne said. “Nutrient contamination is an emerging situation right now. The major concept is nutrient recycling inside the system.”

The potential beneficiaries are wide-ranging. Farmers, growers, and people in arid regions would benefit from utilizing iAVs because the system operates in a controlled environment, meaning it can produce organic food year-round while using far less water than traditional farming. It also offers value as an educational tool, allowing educational and research institutes to showcase a model of sustainable agricultural production.

Ultimately, the hope is that the project inspires a broader shift in agricultural thinking. With increasing strain on global food supply chains, Abeyrathne believes iAVs and similar systems will be essential.

“Food production should be seen through a sustainable lens,” he said. “If we take small steps now, it will make a big impact on the environment, and continued steps will help not only the agricultural sector but the world too."