Tortilla chips paired with fresh salsa are delicious on their own, but imagine enhancing that flavor by growing your own ingredients. Recent research reveals that certain salsa staples—cilantro, bell pepper, and jalapeño—can be more sustainably grown using recycled glass. The findings from this preliminary study indicate that by partially replacing soil with fragments of recycled glass in planters, plants’ growth accelerates and fungal infestations are minimized.
While tortilla chips and fresh salsa are inherently enjoyable, their appeal can be raised if you cultivate the ingredients sustainably. Researchers have discovered that cilantro, bell pepper, and jalapeño can thrive in soil mixed with recycled glass from discarded beverage bottles. Their pilot study showed that incorporating glass fragments into soil helps to promote faster plant growth and reduces the chance of fungal problems.
The findings will be shared at the upcoming fall meeting of the American Chemical Society (ACS).
When nanomaterial scientist Julie Vanegas joined The University of Texas Rio Grande Valley, she began working under the guidance of ecologist Teresa Patricia Feria Arroyo, who focuses on food security and sustainability issues. During their discussions, Vanegas revealed her work with recycled glass particles for coastal restoration, like the cultivation of willow trees. This sparked Feria’s curiosity about whether glass could also be useful for growing food. To address this, they designed experiments with familiar, quick-growing foods suitable for container and backyard gardens—the key ingredients for pico de gallo.
“Our aim is to reduce waste in landfills while simultaneously producing edible crops,” says Andrea Quezada, a graduate student in the Nanoworld Vanegas lab, who will be presenting the research at the meeting. “If successful, we could potentially integrate glass-based soil into farming practices locally in the Rio Grande Valley and even nationwide.”
The researchers obtained recycled glass particles from a company that processes discarded bottles to divert them from landfills. The glass is crushed, with edges smoothed to ensure safe handling, as Quezada notes. This quality allows plant roots to grow around the glass without sustaining damage.
In initial trials, the team evaluated the soil-like attributes of glass fragments of three different sizes. They discovered that pieces similar to coarse grains of sand provided qualities conducive to plant growth, such as good oxygen flow to the roots and moisture retention.
Currently, Quezada is examining the potential of this recyclable glass material as an alternative to traditional soil. In a university greenhouse, she’s nurturing cilantro, bell peppers, and jalapeños in various pots, from 100% commercial potting soil to entirely recycled glass. Although pots containing more soil possess higher nutrient levels vital for plant growth, including nitrogen, phosphorus, and potassium, the pH levels across all pots remain consistent, which is favorable since plants prefer a specific pH range.
Initial results show that plants grown with recycled glass exhibit faster growth and greater water retention compared to those in 100% conventional soil. “A blend containing over 50% glass particles appears to be optimal for plant development,” remarks Vanegas. However, the researchers are waiting until harvest to determine which soil combination yields the best produce and flavor.
In another significant finding, pots with solely potting soil developed a fungus that hindered plant growth. Feria suspects this fungus may interfere with nutrient absorption by roots. Conversely, no fungal growth occurred in pots that contained recycled glass, and the researchers are currently gathering data to understand why.
These findings hold particular significance for Quezada since the study was conducted without the use of fertilizers, pesticides, or fungicides. From her experiences in agriculture, she understands how these chemicals can affect the health of those living or working near farming areas. “It’s crucial to reduce exposure to harmful chemicals,” Quezada emphasizes. “If we manage to lessen their use and engage the community in recycling efforts, we can enhance the quality of life for everyone.”
The research received funding through an Empowering Future Agricultural Scientists grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture, along with a grant from the U.S. National Science Foundation, which also supports Glass Half Full, the company that provided the glass materials.
