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The Herd Beneath The Soil

As you may know, I work part-time for Ecological Farmers Association of Ontario as the Director of Research for the Farmer-led Research Program. In this capacity, I meet wonderful people and farmers, help other farmers conduct research and share their knowledge – all the while learning about farming.  I also get the opportunity to present at workshops and panels across the province. Recently, I gave a presentation at Grey Bruce Farmer’s Week Ecological Day. There was a snowstorm that day (see photo below), so I joined remotely. The organizers asked me to talk about On-farm Strategies for Carbon Storage, so it was back to my roots as a microbial ecologist!  The event was covered by The Rural Voice and the three soil sessions were summarized nicely in an article by Lisa B. Pot (see below).


This is what D, N and T did while I joined the conference remotely from the kitchen!

Sarah  Hargreaves got a bit more serious when she addressed strategies for on-farm carbon storage. She said farmers need to farm microbes which are the key components to trapping carbon deep in our soils. “We need to think like a microbe,” said Hargreaves. “Farmers need to feed their below-ground herd and feed them all year long.” 

Hargreaves is the Farmer-led Research Program Manager for Ecological Farmer’s Association of Ontario and said farmers could be forerunners in offsetting concentrations of atmospheric CO2. The way to do this is by trapping carbon deep in the ground via soil regeneration. “We have come out of a time of soil conservation and data has shown that has largely failed,” said Hargreaves. “We have actually degraded our soil and now we need to regenerate it.” The exciting part is that 1.5 to 5.5 billion tonnes of carbon can be saved in the soil globally. The time to act is now, because soil is actually like a “leaky sink.”

As carbon dioxide rises in the atmosphere, the soil becomes less efficient at storing carbon. Plants play a role. Crop residues play a role and microbes play a role. Scientists used to believe plants played a primary role but there’s been a paradigm shift as the relationship between plants and microbes is revealed. “Plants use carbon to grow but the majority of the carbon is being sent down into the soil for the microbes. Fungi trade nutrients for carbon,” explained Hargreaves. When they receive the carbon and do their work with litter, decaying leaves, crop residues and detritus, the microbes make soil compounds themselves. They leave residues  which form stable compounds of organic matter. “Microbes can even change sand into something with structure and life in it,” said Hargreaves. “The ability of microbes to create soil themselves is very exciting.” Moreover, the microbes stabilize the carbon in soil aggregates. Meanwhile, the aggregates they have created give good soil structure, aeration, water infiltration and resistance to erosion.

Understanding this, farmers can educate themselves about the plant/microbe interaction because it’s the key to locking in carbon on their farms. To get that carbon stored, or sequestered deep in the soils, farmers need to actually farm the soil. By that, Hargreaves means farming to feed microbes. This involves some standard ecological practices that most farmers are already familiar with:

  • Keep the soil covered at all times
  • Maximize crop diversity
  • Keep live roots in the ground
  • Minimize soil disturbance
  • Use organic inputs
  • Capture, sink and store water

“We need to capitalize on the exudates. We need to create a buffer of plants for the microbes to feed on,” said Hargreaves. This can include perennial crops, perennial strips, alley-cropping and multi-species cover crops. “We don’t want to farm naked. No bare fields at any time of the year,” she said.

Read the full article here, including more info about soil life from Mike Dorion of Living Soil and soil health policy in Ontario from Andrew Barrie with OMAFRA.

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