How Compost Captures Carbon and Helps Heal Rangelands and Wetlands

Carbon Capture Carbon Emissions Greenhouse Gases Compost Restoration Wetlands Rangelands California
Marin rangeland and wetland, Inverness, CA. credit: Philippe Vieux-Jeanton

Scientists are in agreement: Global warming is the result of human-caused emission of greenhouse gases, with carbon dioxide as the biggest contributor. We all know that burning fossil fuels is the major source of human-produced carbon dioxide emissions; however oceans, land and vegetation all emit carbon. Carbon has been increasing in the atmosphere since the industrial revolution, largely due to the burning of fossil fuels, but also due to changes in land use.

Due to the demands of population growth, much of California’s rangelands (vast landscapes that grow native vegetation) and wetlands have been converted to cropland and development. Both rangelands and wetlands emit significant amounts of carbon when degraded, but can be restored relatively easily, turning back decades of mismanagement, and regaining their carbon capturing capabilities. We can use plants’ natural appetite for carbon to safely store it while improving the health of our water and soils at the same time.

Save the Bay is working towards the goal of restoring 100,000 acres of tidal marsh habitat around the San Francisco Bay, in order to regain a healthy bay and all its ecosystem services. The Bay has lost 90% of its original tidal wetlands, releasing over 2 billion tons of carbon dioxide. Save the Bay has previously blogged about the carbon capture qualities of wetlands. Research shows that restored rangelands have the ability to capture carbon as well, and it doesn’t take much to restore them.

In the last quarter of a century, over 1950km2 of California rangeland habitats were lost. Rangelands emit carbon not only when converted to other uses, but also when mismanaged, such as through plowing, overgrazing or poor agricultural practices. Native grasslands, primarily through the plants’ extensive and deep root system, are an effective carbon sink, but plowing and converting that land to annual row crops leads to the emission of 20 to 75 metric tons of carbon dioxide per acre.

The Power of Compost

A one-time dusting of compost can make a big difference in restoring degraded rangeland. A study by Rebecca Ryals and Whendee L. Silver concluded that if a thin layer of compost was spread on a quarter of California’s rangeland, the soil could absorb three-quarters of California’s total annual greenhouse gas emissions. The compost fertilizes the soil and improves the soil’s moisture holding capacity, leading to increased plant growth. Through photosynthesis, the plants transfer carbon dioxide from the air into the soil through their roots and decomposing plant material. More carbon in the soil brings greater fertility and water retaining qualities, leading again to greater plant growth, thus sparking an ongoing cycle of regeneration.

From a single application of compost, they found a 50% increase in plant production, leading to an average increase of 1 ton of carbon sequestration per hectare over 30 years. Not only does this provide a relatively easy, low-tech way to launch a positive feedback loop that could play a role in mitigating the effect we’re having on this planet, but you also get increased soil fertility, improved water absorption and retention, and an increase in native plants which provide food for wildlife. Plus, compost can be used to help restore both grasslands and tidal wetlands.

Tidal wetlands have a similar effect. In fact, wetlands store more carbon per unit area than any other ecosystem. Researchers estimate that while grasslands can sink up to 2,000 pounds of carbon per acre per year, wetlands can store up to 5,100 pounds of carbon per acre per year. Similar to the numerous benefits of restoring grasslands, by restoring wetlands we not only sequester carbon, but also absorb floodwaters, reduce storm damage, preserve open space, provide habitat and feeding grounds for a wide variety of species and improve water quality. What’s not to love?

On dry land and wetland, offsetting carbon while increasing biodiversity, improving water quality, providing habitat and improving the environment’s ability to react to climate change is a win-win solution. Clearly, it’s worth our while to conserve and restore rangelands and wetlands, not only to for long-term carbon storage, but also for the numerous additional services they provide. There’s a speck of hope in a sprinkle of compost.

You can get up close and personal with the magic powers of compost through Save The Bay! We use compost to help our native seedlings to grow at our restoration sites around the San Francisco Bay. Learn how you can volunteer with us here.