Episode 47: Soil Carbon with Jennifer Cooper and Jeff Bernicke (NativeEnergy) and Hana Kajimura (Allbirds)

Learn more about the natural environment here!

Episode Intro Notes

What We’ll cover

• What is soil carbon?

• Why is soil carbon important?

• Loss of soil carbon

• How can more carbon be stored in the soil

• Barriers to storing more soil in the carbon

• What can listeners do to help keep more carbon in the soil?

• Jennifer Cooper and Jeff Bernicke from Native Energy and Hana Kajimura from Allbirds

what is soil carbon?

• Soil carbon refers to the fact that soils hold a significant amount of carbon--more than three times the amount in the atmosphere. Only the ocean is a larger carbon sink than the soil.

  • To put it in perspective, humans currently add a little over 4 billion tons of CO2 into the atmosphere annually. The world’s soils contain 1.5 trillion tons of carbon in the form of organic material - or approximately 375 years’ worth of the carbon we annually add to the atmosphere.

• So how does all this carbon end up in the soil? In a couple ways:

  • One way involves photosynthesis. When plants take carbon out of the atmosphere through photosynthesis, some of that carbon, along with nitrogen, gets “fixed” in the soil and acts as a fertilizer.

  • A second way is that when leaves fall and plants decompose, their carbon is absorbed into the soil.

• Soil mainly holds the carbon through its organic matter. Organic matter refers to the fraction of the soil that is highly enriched in carbon since it consists of plant or animal tissue in various stages of breakdown (i.e., decomposition). Organic matter is not a big component of the soil; most of our productive agricultural soils have between 3 and 6 percent organic matter.

• Note that the amount of carbon a soil can hold, known as the carbon budget, differs by soil type.

  • For example, clay-based soils hold organic carbon for longer than sandy soils.

why is soil carbon important?

• Soils with more organic carbon contain more active microorganisms and nutrients, producing healthier plants and grazing animals. In other words, if we pull more carbon out of the atmosphere and into the ground, we’ll get healthier ecosystems and lower CO2 in the atmosphere. It’s our favorite: a win-win!

• On climate change, let’s do a quick refresher on the Paris Climate Agreement before we explain how soil carbon can help us meet our climate goals. In Paris, countries agreed to limit the average increase in global temperatures to 2 degrees Celsius as compared with pre-industrial temperatures. They also agreed to try to keep the average increase below 1.5 degrees. The scientific community believes that above a 1.5 degree rise, our natural system reaches a tipping point and the worst effects of climate change start to occur--significant droughts, sea level rise, more frequent and severe storms, etc.

• To stay below 1.5 degrees, we need to limit our emissions and also enhance our carbon sinks – soil is one of those sinks.

  • The Intergovernmental Panel on Climate Change, which is made up of the world’s leading climate scientists, said in a 2019 report on Climate Change and Land that the potential for soil carbon sequestration in croplands and grasslands is 0.4-8.6 of gigatons of CO2-equivalent per year. The top end of that range is equivalent to almost 1.5 times the annual emissions of the United States.

    • In the U.S. specifically, crop land annually sequesters only 8.4 million metric tons of CO2 equivalent, even though it has the potential to sequester 100 million metric tons each year - so over 10x what’s currently sequestered.

      • When looking at all U.S. soils, including crop land, grazing lands and other types, U.S. soils have the potential to sequester 288 million metric tons each year, which is the same as the greenhouse gas emissions from a little over 60 million cars, or 20% of all vehicles registered in the U.S. today. 

  • Maybe a simpler way to see the potential impact is with the 4 per 1000 initiative that France launched in 2015 at COP 21, which is also where the Paris Climate Accord was reached. The 4 per 1000 initiative brings attention to the fact that a 0.4% increase in the carbon sequestered in the soil globally would be greater than the amount of carbon added to the atmosphere in 2015. So a lot of potential, and even little increases, mean big impact.

loss of soil carbon

• Part of why there is such a big opportunity to store more carbon in soil is because our soils have lost a lot of their carbon. This is largely due to humans altering ecosystems and intensively using land. If you can believe it, the world’s cultivated soils have lost between 50 and 70 percent of their original carbon stock. Over time, this carbon oxidized upon exposure to air and became CO2… which we know to be bad news.

• The carbon lost from the soil has made up a portion of the carbon building up in the atmosphere.

  • Approximately two-thirds of the total increase in atmospheric CO2 is a result of burning fossil fuels. Much of the remainder comes from soil organic carbon loss due to land use change. Common types of land use change include deforestation and clearing native plants for food production.

how can more carbon be stored in the soil?

• Let’s discuss three big ways.

• One is to restore grassland on former crop fields. This can reduce the carbon deficit caused from years of agricultural production. Carbon is sequestered as native grasses and plants develop deeper root systems, which pull and hold more carbon, as compared to crops. 

• Second is to create wetlands and ponds. Wetlands contain a disproportionate amount of the earth's total soil carbon; holding between 20 and 30% of the global soil carbon despite occupying 5–8% of earth’s land surface.

  • The anoxic conditions (meaning low amounts of oxygen) that are characteristic of wetland soils, they slow decomposition and lead to the accumulation of organic matter.

• Third, and this is a big one, is to manage the land in a particular way to reduce carbon loss in the first place or add carbon in. It’s also known as “carbon farming” and “regenerative agriculture.” We’re going to discuss four such management practices. 

  1) Increasing soil stability.

  • This can be done via no till agriculture where crops are grown without disturbing the soil. Think of those big rigs that turn soil over on large farms. This practice can harm soil over time.

  • We can also increase soil stability by employing agroforestry, which is where crop cultivation is intermixed with growing trees and sometimes livestock grazing. Grazing is important to manage since overgrazing with all those cattle eating the grass and leaving the soil bare releases stored carbon.

  • Check out episode 23 on Agroecology for more on this!

    2) Increasing plant and animal inputs

  • Think adding manure and compost. This promotes large and diverse soil microbe communities that break down organic matter and store it as carbon. The microbes themselves also die and contribute to the soil organic matter. Their death is not for nothing….

  • Biochar can also increase organic inputs. This is where organic waste (think trees, crop residues, grass, or other plants) is burned in an oxygen-free chamber and then buried where, under certain conditions, it might sequester carbon for hundreds of years. 

    3) Increasing plant diversity and rotating crops

  • Increased plant diversity and rotating crops can increase microbial activity and build more diverse microbe communities.

    • And plant diversity is definitely something we can work on. Of the 6,000 plant species cultivated for food, just nine account for 66 percent of total crop production. 

      4) Planting cover crops

  • This is where plants are grown on fields after picking, not to harvest, but so that the land is not bare and so it’s less susceptible to disturbance. These crop residues then decay and add carbon to the soil.

    • One study estimated that using cover crops on 25% of the world’s farmland could offset 8% of emissions from agriculture.

• Plus, these practices to add carbon to the soil have co-benefits. They also boost soil productivity and increase resilience to floods and drought. This is why a recent United Nations report found that the economic benefits of land restoration average ten times the costs.

barriers to storming more carbon in the soil

• For farmers, managing their land to increase sequestration of carbon comes with trade-offs.

  • For instance, tilling - which as we mentioned is not so great for storing carbon since it involves disturbing the soil - is often done to control weeds.

  • More generally, these practices may involve investment in new equipment and more time, and result in less land available for cultivation. These can be tough things to add to farmers’ already-full plates.

• It can also be difficult to explain the benefits of soil carbon sequestration since there is uncertainty as to how much sequestration will come from applying certain practices to varying soil types.

• Another barrier is that many people rent their land, which creates less of an incentive to invest in the long-term health of the soil.

  • In the U.S., renters operate almost 40 percent of farmland

what can listeners do to help keep more carbon in the soil?

• Biochar

  • Admittedly, this can be a tough one since we’re pretty sure most of you don’t have your own large farms in your backyards.

  • Also, some of these practices are fairly intensive. For example, we did see one article on DIY biochar but that honestly seemed a little much for the average person.

• Offsets

  • We thought soil carbon offsets you could purchase would be a thing, but apparently storing carbon in soil has traditionally been excluded from carbon markets because it was difficult to measure how much carbon goes into the soil and how long it stays there. This is part of why there are pretty large differences in the maximum amount of carbon that soils could potentially hold. Further,  warming temperatures are thought to compromise the soil’s ability to store carbon.

  • There are some agri-tech start-ups like Indigo Agriculture that are looking into creating carbon markets to incentivize farmers to adopt more regenerative practices. 

• Conscious consumer

  • One thing you can do is tell companies to keep up their soil carbon efforts as part of how they grow food.

    • For example, some big time companies, including Cargill, General Mills, McDonald’s USA and Mars, launched the Ecosystem Services Market Consortium. It encourages farmers and ranchers to adopt conservation management practices to improve soil health and reduce emissions. 

      • Speaking of General Mills, it recently announced it would apply regenerative agriculture to one million acres by 2030. This is about a quarter of the land from which it sources ingredients in North America. This kind of serious commitment makes sense since 50 percent of General Mills’ greenhouse gas emissions come from agriculture. 

    • The yogurt company Stonyfield Farm is developing tools to help farmers easily monitor soil health and learn how to sequester more carbon. 

    • Danone North America recently announced $6 million over five years to fund a soil health research program as part of its regenerative agriculture commitment.

  • There are also products you can buy that were grown in a way that help sequester carbon.

    • For example, Patagonia came out with a beer and Cascadian Farms came out with a limited edition breakfast cereal made with the kernza, a type of wheatgrass, that is a perennial crop. Perennial crops do not need to be replanted each year. This means farmers can avoid plowing the soil, which is something that releases carbon. The supply of kernza is limited for now, but there is the expectation that availability of kernza-based foods will increase.

Jennifer Cooper and Jeff Bernicke from Native Energy and Hana Kajimura from Allbirds

• NativeEnergy is a public benefit corporation and B Corp that since 2000 has worked with hundreds of organizations to develop authentic solutions to their sustainability challenges and implement community-scale projects. They are a perfect group to talk further with about soil carbon because some of those solutions and projects focus directly on soil carbon.

  • For example, they recognized that while regenerative agriculture practices can increase yields for ranchers and farmers over the long term, in the short term they can be too expensive to implement. So they started the Montana Improved Grazing Project. This Project provides farmers financial support for implementing regenerative grazing practices such as high intensity rotational grazing; relieving pressure on waterways so riparian zones along the water can regenerate; and adding compost, soil microbes, and other symbiotic soil species to the soil. 

  • The project started with 35,000 acres under management and intends to expand to 250,000 acres by 2021 and scale from there. The project is funded via NativeEnergy’s Help Build model. Unlike most carbon offsets, sold year-by-year from projects that are already built and operating, Help Build™ investors finance projects with up-front funding needs and a longer-term payback.

• We’re going to dive deeper on soil carbon with two members of NativeEnergy’s team--Jennifer Cooper and Jeff Bernicke.

  • Jennifer Cooper. She’s the VP of Client Strategy at NativeEnergy. She’s been involved in corporate sustainability since 1998 with a stint at Volvo and supporting companies like Johnson & Johnson and Coca Cola. She is based in Pittsburgh but has lived in many countries including in Sweden where she got her masters in environmental management and policy. 

  • Jeff Bernicke. Jeff is the President and CEO of NativeEnergy. He has over 25 years of experience building and leading teams in the development and financing of renewable energy, emissions reduction, and impact projects and programs. He led the development of the Help Build model we just mentioned in a variety of environmental areas. Jay will love this. He’s got his MBA and MS from the University of Michigan.

• Also, to the delight of both our ears and our feet, we’ll be speaking to Hana Kajimura who leads sustainability at Allbirds. Allbirds is an increasingly popular footwear company from New Zealand that uses natural materials like merino wool, eucalyptus tree fiber, and sugar cane in its super comfy shoes.