By Blake Jackson
Researchers at Penn State have found that the design of hydroponic and other soilless farming systems plays a major role in shaping microbial communities, an important finding for a rapidly growing segment of agriculture.
According to the U.S. Department of Agriculture, more than half of tomatoes, cucumbers, and lettuce are produced using hydroponic systems, which help address challenges such as water shortages, limited farmland, and food security concerns.
The study, published in Applied and Environmental Microbiology, examined bacterial activity in five different soilless growing systems while cultivating bok choy. Researchers wanted to determine how system design influences microbial growth and whether those differences could affect plant health and food safety.
The systems evaluated included deep water culture, Kratky, nutrient film technique, ebb-and-flow, and drip irrigation. Among them, the drip irrigation system recorded the highest bacterial counts in nutrient solutions. Scientists found that both system design and the stage of the growing cycle significantly influenced the microbial population and composition.
“The U.S. soilless system food market is a rapidly expanding, multimillion-dollar sector with a market size projected to exceed $6 billion in 2026,” said Francesco Di Gioia, associate professor of vegetable crop science at Penn State.
“Microbial management is a significant challenge in soilless farming, acting as a double-edged sword that can either introduce hazards and increase food safety risks or enhance plant health,” said study senior author Jasna Kovac.
“If introduced into the system, pathogens can spread through recirculating nutrient solutions, making active management of the microbiome a potential tool for their control.”
Researchers measured bacteria in nutrient solutions and on plant leaves. While bacterial levels varied widely among systems, contamination levels on bok choy leaves remained similar.
“In soilless farming, the microbial community can affect plant growth, nutrient cycling, disease suppression, food safety and crop yield,” said Kovac.
“Some microbes are beneficial; some are harmful. Understanding the microbial ecology could help improve soilless farming food safety and productivity, reduce contamination risk and allow the design of safer systems.”
Lead author Auja Bywater noted that microbial communities shifted throughout the growing cycle, although several bacterial groups consistently appeared across systems. Higher nutrient-solution pH was also linked to lower bacterial populations.
“This suggests that the microbiome in the water did not directly translate to contamination on leaves,” Bywater said.
Photo Credit: penn-state
Categories: Pennsylvania, Education