December 28, 2020 at 4:34 p.m.

Mitigating climate change with soil carbon sponge

Discovery Farms virtual conference explores fundamentals
This close-up of a healthy section of soil sponge shows the structural integrity and the wide variety of biology present in the soil.  PHOTO COURTESY OF DIDI PERSHOUSE
This close-up of a healthy section of soil sponge shows the structural integrity and the wide variety of biology present in the soil. PHOTO COURTESY OF DIDI PERSHOUSE

By Danielle Nauman- | Comments: 0 | Leave a comment

    This year’s Discovery Farm Conference is being conducted in a series of weekly webinars.
    The first in the series beginning in December, under the theme of “Keeping Up with Your Conservation Goals Through Change and Challenge,” was focused on mitigating climate change through the soil carbon sponge.
    Walter Jehne, an Australian microbiologist and climate scientist and the director of Regenerate Earth, and Didi Pershouse, of Vermont, an author and the founder of the Land and Leadership Initiative, shared what they have learned from their experiences and research on mitigating climate change.
    “The challenge is really fundamental because things are changing, the climate is changing,” Jehne said. “In Australia, we have had extreme hot weather, 40 to 50 degrees centigrade, with really serious impacts like wildfires. Last summer, we lost half of our whole forest. We have a fundamental challenge across all parts of agriculture, all countries. How do we address these hydrological climate extremes?”
    Jehne explained the challenge lies at the grass-roots community level, the individual farmer level, to address these problems.
    “It’s all about building resilience in our ecosystems,” Jehne said. “How do we take our existing landscapes, farms, agriculture and forests; and how do we build resilience in those systems so they can buffer these changes? It also applies to our social systems because the (coronavirus) has shown us we are more vulnerable to these extremes. What did nature do to create resilient, buffered, productive biosystems and what can we do to restore them?”
    The answer, according to Jehne, boils down to regenerating the earth’s soil carbon sponge, and we can use those same systems that nature used to rebuild resilient biosystems, cool the planet and stabilize what could be serious impacts.
    “It is what nature did,” Jehne said. “It took carbon dioxide from the air, through plant photosynthesis, biosequestered it in the soil, creating the soil carbon sponge. In that process, was able to basically build the hydrology of the planet, the biosystems, the forests, the vegetation, the animals, all those ecosystems we depend on; and through that hydrology, naturally cool and stabilize the climate.”
    Pershouse explained how the earth’s carbon sponge works.
    “One aspect of a sponge is the structural integrity of it,” Pershouse said, talking about a household sponge in comparison to a soil sponge. “Another thing is its capacity to hold water. For a soil sponge, you want it to soak up water and keep it at the plant root zone for later use, and to filter through to fill our wells and aquifers, and to slowly fill our lakes, rivers and streams from the sides the bottoms, not from the top. We aren’t looking for more runoff.”
    Pershouse used the analogy of a plate of flour, explaining that the loose flour has no structural integrity. When rain impacts soil that has no structural integrity, the water runs off and creates erosion, because the soil is unable to act as a sponge.
    “The lack of a soil sponge is a major factor in the algal blooms that we are seeing, and in flooding and drought, which are really two sides of the same issue,” Pershouse said. “It is a major factor in the length of the green season and in the health and resilience of crops, and by extension in the health of the animals and humans that eat those crops.”
    In continuing her analogy, Pershouse said that to change flour into bread, you need to change biology; for the soil, that biology comes in the form of plant roots that feed the biology in the soil and help the mineral particles stick together, building the structure of the soil.
    “As the plant roots, fungal hyphae, worms and other life moves through there, you suddenly get a porous structure,” Pershouse said. “You will see in healthy soils, that something that has the structure is affected differently by the rain that falls, soaking it up. It goes down the roots to the plants; there is no erosion happening, no mudslides. There is protection against drought, that water is held for all the life in the soil. And you will see when the water does start coming out to fill the lakes and streams, it is filtered and pure.”
    Pershouse expounded on the importance and fragility of the soil sponge, and the conditions needed for it to thrive.
    “The soil sponge is the fundamental infrastructure for life on land,” Pershouse said. “It underlies all successful human economies and societies, but humans cannot build this infrastructure. It requires a diverse biological workforce. We need to let this biological workforce build the sponge and not disturb it with plows.”
    Jehne said only 4% of the earth’s heat dynamics are a result of carbon dioxide, but that 95% of the heat dynamics are governed by water.
    “By managing the sponge, we can enhance and restore the management of the hydrology, so that we can use that to buffer and mitigate climate change, so that we can naturally and safely cool the planet,” Jehne said.  
    The Wisconsin and Minnesota Discovery Farms programs are a farmer-led research and outreach group focused on the relationship between agriculture and water quality, all of the presentations of the series are available on YouTube.


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