Dishing the Dirt During the Holidays
When you sit down at the table to celebrate the holidays, along with giving thanks for family and health, be sure to give thanks for the rich agricultural soil that produced your dinner. I learned this from Anne Stauffer, co-organizer of the Sierra Club's Loma Prieta Soils Committee and the recently formed Sustainable Agriculture Committee within Sierra Club California.
Stauffer grew up in Bakersfield, went to school with farmers' kids, and majored in biology in college. But it wasn't until she read Kristin Ohlson's book, "The Soil Will Save Us," that Stauffer became dedicated to soil health and the new field of regenerative agriculture.
Healthy soil has many benefits — it stores carbon and other necessary elements, absorbs and holds onto water, provides sustenance to the myriad of microorganisms needed for plant health, and overall provides a happy growing medium for plants.
If the microbes that nurture soil productivity die, what is left is infertile, dry dust – the kind that covered the Southern Plains during the 1930's Dust Bowl .... But agriculture can also be harnessed to restore the land while solving another serious problem: global warming. "
Soil becomes healthy through the power of photosynthesis. Plants use the sun's power to absorb carbon dioxide and give off oxygen. The absorbed carbon combines with water and other elements and passes into the plant's root system as a sugar; this sugar is used by soil microbes as food. In return, microbes provide necessary nutrients to the plants. When the microbes die, they release carbon into the soil for other microorganisms to use. This ongoing process gradually builds up soil organic matter.
Carbon is so important that soil organic matter typically contains at least 50% carbon. Walking through a redwood forest, you can feel a spongy soil under your feet. That is the result of a long-term build-up of organic matter full of millions to billions of microbes.
Unfortunately, conventional agriculture has been responsible for the degradation of much of the agricultural soil. For example, synthetic fertilizers decrease soil microbial activity. Plants treated with synthetic fertilizers don't need to interact with soil life-forms as much and, instead, increasingly depend on the fertilizer. As these soil life-forms die off or move elsewhere, soil health declines.
Conventional agriculture also uses repeated tilling, which breaks up the structure that holds soil particles together and releases carbon into the atmosphere. The carbon combines with oxygen and becomes carbon dioxide (CO2).
Soil exposed to air by tilling soon dries out, and the nutrients blow away. If the microbes that nurture soil productivity die, what is left is infertile, dry dust – the kind that covered the Southern Plains during the 1930's Dust Bowl. Other contributions to poor soil health include growing the same crop over and over, and using pesticides and herbicides.
But agriculture can also be harnessed to restore the land while solving another serious problem: global warming.
Last month, the United Nations Intergovernmental Panel on Climate Change (IPCC) released an alarming report that stated it would take a vast, unprecedented global effort to limit the devastating effects of climate change. Part of that effort would be to limit the burning of fossil fuels; another part would be to draw carbon out of the atmosphere and store it. One place to store that carbon is by using soil as a carbon sink or a reservoir for carbon, a process called carbon sequestration.
Globally, over one third of arable land is used for agriculture. Think of the impact, if we can employ regenerative agriculture worldwide to increase soil carbon in agricultural soil!
Stauffer outlined some of the proposals for regenerating soil and sequestering carbon.
1. Use non-till farming. Non-till farming preserves the soil structure that helps to lock carbon into the soil.
2. Grow cover crops. Non-food crops grown during the off-season can put down roots that sequester carbon, slow down erosion, and promote better soil health.
3. Leave the cover crops in place. Leave the green matter on the surface and the roots in the soil, to decay and enrich the earth.
4. Grow crops with deep roots. The deeper the roots, the deeper the carbon is placed and the longer it stays in the ground.
5. Plant diverse crops. Crop rotations using different plants may contribute higher soil carbon and soil microbial biomass than less diverse systems.
6. Spread compost on top of the soil. Even a thin layer will enrich the soil beneath it.
7. Use less synthetic fertilizer. This encourages stronger root development.
8. Plant perennial crops. If the same plant produces a crop year after year, an extensive root system can develop.
9. Plant hedgerows. Dense rows of trees and shrubs provide protection from wind erosion as well as a rich habitat for wildlife.
10. Rotate farm animals on the land. Instead of muddy, lifeless feed lots, rotate cattle or sheep through a series of pastures. The native forage grasses have a better chance to survive and can even thrive, as the critters massage and fertilize the soil by doing what they do naturally after they digest their dinner.
Our state has started to try some of these new approaches to farming. California has established a Healthy Soils Program as part of its Climate Smart Agriculture program. Since California has over 43 million acres of agricultural land, this could result in an enormous amount of carbon being sequestered in California's soil.
For Stauffer, the changes needed for agriculture are not that complicated. Her biggest challenge is figuring out how to get people to change. Except for farmers, most of us don't think about soil — we just walk on it. And yet, as Stauffer says, "soil is the reason we are all here."
In a future article, we will talk about how you can apply the principles of regenerative agriculture to your own garden. Meanwhile, enjoy your holiday feast and give thanks to the web of life that produced it.
Join Stauffer in her efforts at:
Learn more about regenerative agriculture at:
Learn more about California's agriculture programs at:
Watch fun videos here:
Katherine Howard is a member of the Executive Committee of the SF Group of the Sierra Club.