Getting Down to Earth: Carbon Sequestration Explained
by Alex Stock, from climable.org
Since the age of industrialization, humans have been emitting so much carbon dioxide that we now need to remove carbon from the atmosphere. While there are plenty of viable strategies out there, there’s one deceptively simple solution that lies right beneath your feet— soil! To learn more, I chatted with Karl Thidemann from Soil4Climate about the vast potential of soil as a carbon sink.
If you’ve taken a biology class, you learned about photosynthesis. Plants pull carbon dioxide out of the air during photosynthesis and turn that carbon into simple sugars for food. The plant uses some of these sugars as building blocks to grow its stems, leaves, and other structural components. But some of these sugars get pumped into the ground to feed microscopic soil life, like fungi and bacteria, sustaining an underground ecosystem. Soil life is key to providing nutrients and minerals to the plant. So while some of the atmospheric carbon absorbed through photosynthesis is stored in the plant itself, a lot of it is stored in soil as well— but soil can’t capture carbon by itself. The soil and the plants have an immensely important symbiotic relationship. Plants feed the soil life, and the soil life provides nutrients and minerals to the plant, all while pulling carbon from the air.
Soil has a huge potential to store atmospheric carbon, but our current agricultural system doesn’t prioritize soil health. Monoculture (farming of 1 crop per field) and the extensive use of synthetic fertilizers inhibit soil life and prevent it from storing carbon. Furthermore, industrial agriculture is fossil-fuel intensive and emits over 9% of all greenhouse gases in the US. But Karl notes that growing food has the potential to become a carbon-negative endeavor if we begin practicing regenerative agriculture.
Regenerative agriculture is a method of farming that focuses on replenishing the health of the soil to allow it to absorb more carbon and improve crop yields. Karl explained several key regenerative agriculture practices, starting with avoiding synthetic fertilizers. Pesticides, fertilizers, and herbicides are responsible for algae blooms, human health problems, and degraded soil. Over time, these chemicals kill the soil life and crop yields decrease. Another important practice is called no-till. Farmers traditionally till soil to aerate it before seeds are planted, but this disrupts the delicate fungal network in the soil, preventing nutrients from getting to the plant. By tilling as little as possible, these networks stay intact. It’s also important for farmers to keep the soil covered by rotating crops, proper grazing management, and using cover crops, which prevents erosion and feeds the soil year round. All of these tactics help grow and protect healthy soil, allowing it to store more carbon and mitigate the impacts of climate change.
It’s difficult to know if your food has been farmed regeneratively. Unlike organic foods, there’s no USDA certification for regenerative produce. Nevertheless, supporting local organic farmers is always a good bet. Check out The Organic Food Guide to find some near you!