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��Compost, Soil Carbon, and Climate Resilience in Fremont

Lori Caldwell, StopWaste

March 10, 2025

Presented by:

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What do you notice?

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Soils contain more carbon than plants and atmosphere combined!

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Making and using compost

Home compost

Commercial compost

LEAF’s (Local Ecology and Agriculture Fremont) compost system

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Carbon Farming Research – Marin Carbon Project

Marin Carbon Project Story: John Wick owns a ranch in Nicasio. The ranch has been grazed for over a hundred years. When he and his wife moved the ranch they had dreams of restoring the original oak woodland/grassland, so they ended the grazing and thought the landscape would take care of itself, but it didn’t. What happened was that coyote brush took over and the land continued to degrade. They hired an ecologist to help them, and in December 2008, John Wick spread ½ inch of compost over two one-hectare plots, by May 2009 they found 1 metric ton of carbon in each plot. The project expanded to include Whendee Silver’s lab at UC Berkeley and UC Extension to gather and analyze data over the next 5 years. Subtracted the carbon from the compost.

1 Mg of Carbon = 3.7 Mg of Co2e

Equivalent to carbon sequestered by 1.7 hectare of forest

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Carbon Farming Research – Marin Carbon Project

Compost stimulated plant growth and increased photosynthesis
Plants convert co2 and “deposit” carbon rich “exudates” in soil
Native perennials, with deeper roots than annuals, deposit carbon deep into soil profile
Average carbon sequestration: 1 Mg/hectare-year, continuing every year for 30 years

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StopWaste - Altamont Hills with ACRCD and UC Merced

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Test Plot increases soil carbon, Control Plot loses soil carbon

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Parks – Cities of Dublin and Pleasanton, UC Merced

Above photos – City of Pleasanton’s Ken Mercer Sports Field

Soil Survey of 8 parks

2 with 20+ years of compost application

6 with never receiving compost

Left photos – City of Dublin’s Emerald Glen Park

Experimental plan with compost and control plot

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High soil carbon in urban farms in Alameda County

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Local Ecology and Agriculture Fremont – LEAF’s Carbon Data

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Carbon farming practices

Compost and worm castings
Mulch
Sheet mulching
Plant deep rooted perennials
Plant cover crops
Plant a diversity of species
No tilling
No synthetic fertilizers, pesticides, and herbicides

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Free StopWaste resources

The Nitty Gritty
The Worm Count
The Slake Test
8 total activities in StopWaste’s Healthy Soils Activity Guide

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The Nitty Gritty – Visualize your soil type

Sandy clay

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The Worm Count – Measure your organic matter

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The Slake Test – Examine your soil stability

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Gill Tract Farm, Albany

Pleasanton Community Farm

Fertile Groundworks, Livermore

Farm2Market, Alameda

Compost Hubs!

Free compost giveaway programs, offered year round

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StopWaste resources

Website and downloadable resources

Healthy Soils Activity Guide
Tools For Building Healthy Soil
Urban Farm Volunteer Opportunity Map
www.StopWaste.org/gardening

Free compost at local Compost Hubs!

www.StopWaste.org/CompostHub

Compost Happens! In Alameda County Video

https://youtu.be/Z3ez7qsRwV8?si=ilnQH7aBS1V0FpNG

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Thank you!��www.stopwaste.org/gardening

Lori Caldwell

lcaldwell@stopwaste.org