Today’s Solutions: December 18, 2025

While it’s well known that compost made from food scraps helps plants grow, scientists have now figured out how to create a liquid fertilizer out of fermented food waste, which can boost beneficial bacteria within plants making them more resistant to pathogens and reducing carbon emissions from farming.

Conducted by scientists at the University of California-Riverside, the research involved two types of food waste, namely mash leftover from the beer production process and mixed food items discarded by grocery stores.

Through fermentation, the scientists converted the organic waste into a liquid known as a digestate. They then added the liquid to the water used to irrigate citrus plants in a greenhouse. Within just 24 hours of the digestate being added, the researchers found that the populations of beneficial bacteria within plants were three times larger than those in a control group.

On top of helping plants grow stronger and faster, the benign bacteria made the plants more resistant to disease. Not only that, but the researchers also observed that the carbon levels in the water initially peaked after the digestate was added, then sharply decreased. This suggests that the bacteria were using the carbon to reproduce.

The team now hopes to scale up the technology and thus reduce the need for or even replace conventional fertilizers — which are typically more expensive and environmentally unfriendly — all while diverting huge amounts of organic waste from landfills.

“We must transition from our linear ‘take-make-consume-dispose’ economy to a circular one in which we use something and then find a new purpose for it,” says study lead author Deborah Pagliaccia. “This process is critical to protecting our planet from constant depletion of natural resources and the threat of greenhouse gases.”

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