- Researchers studied a Japanese organic farm with 50+ years of low soil-borne disease incidence.
- Organic fertilisers significantly increased Lysobacter, a pathogen-suppressing bacterium.
- However, researchers could not consistently show that organic fertiliser application boosts Lysobacter populations.
Soil-borne diseases remain a major challenge for organic agriculture as it does not rely on synthetic crop protection like conventional farming.
However, an organic farm in Shiga Prefecture of Japan has claimed to have little soil-borne disease for over five decades despite the limited use of chemical crop protection tools.
While naturally disease-suppressive soils have been reported around the world, scientists have not fully understood the microbial factors that have made fields resistant pathogen outbreaks.
Researchers from the Nagahama Institute of Bio-Science and Technology set out to study the organic farmland, which has been managed by Shimamoto Microbial Industry.
For this study, they analysed soil microbial communities and examined how they responded to different organic materials.
The researchers observed that adding organic fertilisers such as rice bran and protein-rich organic matter increased the abundance of Lysobacter bacteria, which has been known to suppress plant pathogens.
This led the researchers to hypothesise that Lysobacter could be one factor contributing to the organic farm’s long-term resistance to soil-borne diseases.
Not as simple as it seems
Crucially, boosting the presence of Lysobacter in soil was not as simple as applying fertiliser, the researchers found.
When the team expanded its tests to a total of 24 farmlands, primarily in Shiga Prefecture, it observed that Lysobacter populations did not respond to protein-rich organic matter the same way every time.
Notably, the differences could not be explained solely by whether fields were managed organically or conventionally.
Instead, the study found that pre-existing soil microbial communities and environmental conditions played a significant role in determining how strongly Lysobacter populations increased following organic matter application.
The results indicate that efforts to enhance disease-suppressive microorganisms may need to be tailored to individual fields rather than relying on a one-size-fits-all approach.
“Further verification is needed to determine whether Lysobacter directly suppresses disease, but we believe that understanding the microbial community of each farmland and harnessing its power will lead to sustainable agriculture that reduces the use of pesticides.”
The researchers said the future research should support technologies designed to create soil environments that favour beneficial microorganisms, potentially enabling more farms to develop natural disease-suppressive capabilities.
Building on the findings, Nagahama Institute of Bio-Science and Technology, Shimamoto Microbial Industry and Candy Farm are developing a soil disease management technology based on Lysobacter bacteria.
The partners are seeking to combine Lysobacter, organic fertilisers and biochar into a microbial product.
The goal is to establish a technology capable of transforming conventional farmland into disease-suppressive soils by encouraging beneficial microbial communities.
Source: Journal of Bioscience and Bioengineering
Enrichment of Lysobacter in a long-term organically managed agricultural field with low soilborne disease incidence
Authors: Seiji Kamba, Motomu Kuroki, Ikuyo Takemura, Hiromasa Tabata, Ryuhei Minei, Mitsuhisa Shimamoto, Atsushi Ogura, Makoto Hasegawa, and Masahito Ishikawa.
https://doi.org/10.1016/j.jbiosc.2026.07.002
