Soils on organic farms host more diverse and beneficial communities of fungi compared to conventional farmland, according to a recent study published in the journal Microorganisms. The improved soil microbial diversity fosters species that promote plant growth and suppress diseases, in contrast to healthy organic soils, more harmful microbes were found to be more prevalent in conventional systems. 

Because organic farmers can’t use chemicals to fertilize or fight soil diseases, they must rely on ecosystem services provided by soil microbes, such as nutrient recycling, growth promotion, and disease protection. When agrochemicals are used on conventional farms, they disrupt microbial communities by altering resource availability and soil conditions and directly killing microbes. Previous research has shown that pesticides reduce populations of pathogen-fighting bacteria, increasing disease susceptibility. 

The study, which was conducted on tomato farms in Japan, compared soil from long-established organic farms (with and without organic fertilizers), long-standing conventional farms, and newly established conventional farms. Results revealed that organic farms had a greater presence of beneficial fungi and a more balanced fungal community relative to conventional farming. These soils had higher quality indicators, such as more carbon, phosphorus, potassium, and calcium, which are physical properties that support the healthy function of microbial communities.  

Beneficial fungi were notably more abundant in organic soils. For example, Tremellomycetes fungi, found across the organic treatments, promote plant growth and emit pathogen-deterring chemicals. Pure organic soils hosted exclusive species like Linnemannia fungi, known for growth promotion. Importantly, pathogenic Fusarium fungi, which can cause catastrophic damage to tomato (and other) crops, were absent from organic soils, but common in conventional soils. 

This research demonstrates that avoiding synthetic chemicals can create a healthy fungal community and soil ecosystem that provides the backbone of organic regenerative farming.