Healthy Soils - 101
Good stewardship of soil–at your home, school, or workplace–is one of the most important things you can do for the planet!
“Soils contain approximately 75% of the carbon pool on land–three times the amount stored in all living plants and animals.” (Ecological Society of America) Soils hold 3 times the carbon contained in the atmosphere, and we’ve lost 50-70% of the carbon it once held; land management is responsible for 25% of global greenhouse gas emissions. (Columbia University)
Building Healthy Soils:
Planting trees and establishing pollinator and wildlife habitats of native plants can help store carbon, but prioritizing soil health in turn keeps trees and plants healthy. Our urban or residential soils often have altered textures with more clay and more sand than before development. Organic matter in soil, largely carbon from decayed plant and animal matter, holds plant nutrients, improves soil texture and structure, and helps moisture levels stay just right for plants. Often topsoil gets removed during construction, leaving less developed, less loamy soil with less of that desirable organic matter. A healthy soil is about 45% mineral content, 5% organic matter, and 50% porespace for air and water, but development, heavy machinery, and foot traffic can leave us with soils with only 1-2% organic matter and 25-30% porespace. (CSU Extension - click on the pie charts below to zoom in) This limits the oxygen plant roots need and slows water infiltration.
To remediate compaction, carefully and selectively loosen your soil (preferably with a fork rather than by tilling). Plan to do it only once, and create pathways in order to keep foot traffic off soil. The first footstep causes up to 75% of the possible compaction, with 90% possible compact reached by the fourth pass. (CSU Extension) Mulches and amendments like compost help protect soil and build up soil flora and fauna (bacteria, fungi, and tiny creatures which help work organic matter into the soil and improve its structure and texture for plants). Plant-based compost is the best amendment or mulch you can use. If locally sourced (or created at home), it helps keep our carbon and nutrients local. Plant-based compost, used in the proper amount (1-3” depth) doesn’t have the pollution problem that synthetic fertilizers do, is low in embodied carbon (it doesn’t require a lot of fossil fuel inputs), and will not salt up our soils. (CSU Extension) It provides slow-release nutrients which will not leach out of soil. Locally-sourced wood chips are another way to mulch plants and keep up our carbon circularity. Both of these can help slowly increase soil organic matter over time. An increase of just 1% in soil organic matter helps store 11,600 lbs of carbon (Pennsylvania State Extension) and 20,000 gallons more water per acre (NRDC).
Composting for Community Initiative at the Institute for Local Self-Reliance
[U.S. Environmental Protection Agency. (2020) Composting Food Waste: Keeping a Good Thing Going. Southeast New England Program. https://www.epa.gov/snep/composting-food-waste-keeping-good-thing-going]
Composting is arguably the single most important thing you can do to combat climate change.
Composting lowers the emission of carbon dioxide, methane, and nitrous oxide (all potent greenhouse gasses), allows carbon to be sequestered in soil, and reduces the need for energy intensive, natural-gas based synthetic fertilizer. Check out information on home composting provided by EcoCycle, Boulder County and CSU Extension, and be aware that curbside composting guidelines are changing in order to reduce contamination!
More great resources and information for frugal gardeners can be found at the Resource Yard, CSU Extension, Resource Central, and beyond!