Discover how compost and mulch build healthy soil for gardens, landscapes, and agriculture. Find local sources, how-to guides, compliance tools, and training programs across Alameda County.
Home compost (left) and commercially-produced compost from organics collected in the green bin (right)
Healthy soil is the foundation for any garden, landscape, and farm, and compost and mulch are versatile tools for building healthy soil and feeding the soil ecosystem. Applying compost and mulch builds soil organic matter, improves soil water holding capacity, reduces erosion, and sequesters carbon to mitigate climate change.
Locally produced compost and mulch are products of recycled organic materials such as food scraps, green waste, and tree trimmings and play an important role in diverting organics and preventing methane emissions (a potent greenhouse gas) from the landfill.
StopWaste collaborates with local community organizations, agencies, and composters to provide education and resources on how to make your own compost, how to access bulk compost, and how to properly use compost in gardening, landscaping, and agriculture. Please reach out with questions or opportunities after viewing our resources below.
Tools and resources for jurisdictions and landscape professionals to comply with California's compost procurement, water efficiency, and turf irrigation laws.
Access compost technical assistance, trainings, educational workshops, and volunteer opportunities across Alameda County.
Accordion
Compost is a dark, crumbly, earthy smelling soil amendment, similar to the humus that accumulates on the forest floor. Compost is the product of controlled aerobic decomposition, resulting in a stable form of organic matter that is beneficial for soil health and plant growth. Additionally, the composted materials undergo both ambient and hot temperatures (131F +) during decomposition, which significantly reduces pathogens and weed seeds in the finished compost.
Despite the resemblance, compost is not soil — rather, compost is always used to amend existing soil. Compost is also not a fertilizer — it does supply some plant nutrients to the soil, however the primary "nutrient" in compost is actually carbon! Carbon provides energy to the plethora of beneficial bacteria, fungi, and invertebrates which in turn facilitate nutrient cycling and soil development. Using compost feeds the soil ecosystem, affects soil structure, density, and texture, and helps soil act as a sponge by improving soil moisture retention and drainage.
Mulch is a material applied to the surface of the soil. In nature, leaves, branches, and needles fall to the ground, creating an organic mulch layer that protects and builds the soil. Mulch produced from locally recycled tree and plant trimmings offers the same advantage, helping to suppress weeds, reduce evaporation of soil moisture, regulate soil temperature during extreme weather, and prevent erosion. Grass clippings, leaves and tree trimmings that are chipped or shredded are readily available forms of recycled mulch and can be used in tandem with compost to manage soil health. "Organic" mulches made from recycled tree and plant trimmings feed the soil as they decompose in place, contrasted with "inorganic" mulches like rock.
Weed barriers are often applied below the mulch layer to further suppress weeds. Plastic fabric weed cloth is inorganic, is only effective in the short term, and inadvertently pollutes the soil with microplastic fibers. Cardboard is an alternative weed barrier that smothers weeds and additionally feeds the soil as it decomposes over time.
What does composting look like in Alameda County?
Looking for more background information on compost? "Compost Happens in Alameda County!" takes a look at various composters around Alameda County and the East Bay to see how yard waste and food scraps are transformed into compost used by local gardeners, landscapers, and farmers.
