Garden Soil Carbon Estimator
See the rough range of carbon your garden soil could build each year.
This tool was built by Serge, MSc., a plant biologist and environmental scientist with a BSc in Plant Biology and an MSc in Environmental Biology and Biogeochemistry. My research focused on how climate warming affects soil carbon cycling in boreal forest ecosystems. These tools are for educational purposes and give practical guidance, not professional advice.
Soil stores carbon when you add organic matter and stop disturbing it. How much any plot gains depends on soil type, climate, and how long you keep the practice up, so no tool can give an exact figure. This estimator uses published sequestration rates to show a realistic range for your bed size and chosen practices, to help you compare approaches, not to certify a number.
Please enter a bed area above zero and choose a practice.
How this works
Published field studies report soil organic carbon gains from best practices in a broad band, roughly 0.2 to 0.5 tonnes of carbon per hectare each year for regular organic inputs, and up to around 1 tonne per hectare per year where compost, cover crops and no-dig are combined. The tool converts your bed area to hectares, multiplies by the low and high rate for your chosen practice, and shows the result as a range. It deliberately does not give a single number, because the real figure depends on conditions this tool cannot see.
Understanding your result
The figure is carbon added per year while you keep the practice going. It is not permanent or unlimited. Soil carbon rises fastest in the first years, then slows as the soil reaches a new balance, so do not multiply this by many years and expect a straight line. To convert carbon to carbon dioxide removed from the air, multiply by about 3.67, since each unit of carbon corresponds to that much CO2 by mass.
Important limitations
This is an educational estimate, not a measurement. Actual gains vary several-fold with soil texture, starting carbon level, climate, and how consistently you add organic matter. Carbon already stored can be lost again if you return to heavy digging or leave soil bare. For a proper site-specific estimate, the USDA COMET-Farm tool models management scenarios in detail.
Scientific basis
- FAO, soil organic carbon sequestration in croplands (0.11 to 1.92 t C per hectare per year): FAO / Food Forward NDCs
- Review of measured sequestration rates (0.2 to 0.5 t C per hectare per year from best practices), ScienceDirect: sciencedirect.com
- USDA COMET-Farm modelling tool: comet-farm.com
Disclaimer: This estimator gives a general educational range only and is not a measurement or a certified carbon figure.