Microbial management is a significant challenge in soilless farming.
A new study from Penn State researchers shows that the design of hydroponic and other soilless farming systems can significantly influence microbial communities, providing important insights for an expanding agricultural sector.
Hydroponic production has been growing in recent years. The U.S. Department of Agriculture reports that more than half of the country’s tomatoes, cucumbers, and lettuce are grown using hydroponic systems.
Published in Applied and Environmental Microbiology, the study investigated bacterial activity in five soilless systems while growing bok choy. Researchers compared deep water culture, Kratky, nutrient film technique, ebb-and-flow, and drip irrigation to understand how system design and crop development affect microbial populations.
The drip irrigation system had the highest bacterial counts in nutrient solutions. Researchers also found that microbial communities changed depending on both the growing system and the crop’s developmental stage. However, despite differences in bacterial levels within nutrient solutions, contamination on bok choy leaves was generally similar across the systems.
“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.
Researchers emphasized that beneficial and harmful microorganisms can affect plant growth, nutrient cycling, disease suppression, food safety, and crop yields.
Lead author Auja Bywater also found that microbial communities shifted throughout the growing cycle, while certain bacterial groups remained common across systems.
Higher nutrient-solution pH was associated with lower bacterial populations. “This suggests that the microbiome in the water did not directly translate to contamination on leaves,” Bywater said.
The findings could help growers better manage microbial communities and improve the safety, productivity, and design of future soilless farming systems.
Photo Credit: penn-state