Organic farming builds drought-resistant avocado root microbiomes by enriching Bacillus bacteria, study finds

Long-term organic farming reshapes the bacterial communities surrounding avocado roots in ways that make the trees significantly more resistant to drought, according to research published in npj Biofilms and Microbiomes.

Spanish researchers collected rhizosphere soil samples from avocado orchards managed under conventional and organic systems across southern Spain, a region where drought stress is an increasing production risk. They found that organic management, applied consistently over years, enriched populations of Bacillus species — bacteria known for their ability to colonize plant roots, produce drought-protective compounds, and mobilize soil nutrients under water-limited conditions.

Conventional orchards in the same area did not show the same enrichment of Bacillus populations, suggesting that synthetic fertilizers and pesticides suppress or fail to encourage the microorganisms that confer resilience. The organic management regime — which includes compost applications, cover crops and no synthetic inputs — appears to create conditions in which beneficial bacteria can establish at scale.

The findings carry practical weight for specialty crop producers and fertilizer companies developing biostimulant and biofertilizer products for perennial fruit systems. Bacillus-based inoculants are among the most commercially developed microbial inputs on the market, used in products for drought tolerance, phosphate solubilization and plant growth promotion. The study provides field-scale evidence that organic soil management systems can produce similar outcomes to inoculant application — or create conditions that make inoculants more effective.

Water scarcity is an intensifying constraint for avocado production in Spain and across Mediterranean growing regions. As synthetic fertilizer costs remain elevated and demand for organic and sustainably grown produce continues to grow, the economic and agronomic case for organic transitions in perennial fruit farming is gaining both biological and commercial support.

Source: Phys.org