A McGill University study suggests that diversifying crops and replacing annual wheat with a perennial grain could help protect soil health as climate change brings more variable rainfall.

Researchers tested two approaches at McGill’s Emile A. Lods Agronomy Research Farm in Ste-Anne-de-Bellevue: growing multiple crops next to each other in alternating rows – one form of a practice known as intercropping – and replacing annual wheat with intermediate wheatgrass, or Kernza, a niche perennial grain used for products like bread and beer but unlike conventional wheat in taste and composition.

Both strategies affected the soil’s microbial communities, which play a key role in plant health and nutrient cycling.

The findings show that both intercropping and the perennial system increased beneficial fungi associated with plant roots and changed how microbial species are structured in the soil.

“We found that both intercropping and replacing the annual wheat with the perennial grain… increased the abundance of a beneficial fungal symbiont,” said Deniz Dutton, first author of the study who completed the research as a Master’s student in the Department of Natural Resource Science.

Soil microbes are essential for such processes as nutrient cycling, carbon storage and plant resilience. Conventional farming systems that rely on single crops can weaken these microbial communities and make soils more vulnerable to drought and flooding.

The study also revealed that as crop diversity increased, so did variability in microbial communities. The researchers say this variability could help soils adapt over time by ensuring some microbes are suited to changing conditions.

To reach these conclusions, the team carried out field sampling and lab analysis. Plots were exposed to simulated rainfall changes using shelters that reduced precipitation by 30 per cent and systems that redirected that water to neighbouring plots. The team then analyzed soil DNA and microbial activity in the lab to understand how communities responded.

The research builds on growing interest in agricultural practices that can improve resilience while reducing environmental impacts.

“The science points to a need to change our agricultural practices to make them more resilient to climate change and at the same time to reduce the contributions of agriculture to climate change,” Dutton said.

Historically, many farming systems relied on more diverse crop rotations and ecological practices before synthetic pesticides and more uniform, input‑intensive agriculture became widespread in the mid‑20th century.

“Diversified and perennial agriculture was used previously to provide insurance against crop failure and also to regenerate the soil’s fertility,” she said.

Dutton said the study offers a starting point for farmers, policymakers and others interested in climate-resilient agriculture.

She said she hopes future research will examine how alternative cropping systems perform over time, especially as weather extremes intensify.

Diverse and perennial cropping systems alter microbial community structure and increase the spatial variability of microbial diversity and functioning under a precipitation gradient by Deniz Lara Dutton, Cynthia Kallenbach, Mary-Cathrine Leewis, and Visveshwar Senthilkumaran, was published in Applied Soil Ecology. It was funded by the National Science and Engineering Research Council of Canada and by the Fonds de recherche du Quebec - Nature et technologies.