Soil Carbon Sequestration and Climate Change

Soil Carbon Sequestration

Soil holds so much carbon that it is the largest organic carbon reservoir on land. However, due to unsustainable soil management practices, soils are being eroded and losing SOC, which not only threatens soil health and food production, but also contribute significantly to climate change by carbon-based greenhouse gases (GHG) emissions.[1]

Agriculture has long been a net emitter of greenhouse gases because of unsustainable farming practices that deplete SOC. It is estimated that 30% to 75% of original SOC in most agricultural soil has already been lost.[2] Contemporary food systems accounts for 29% at most for total global anthropogenic GHG emissions, of which agricultural productions including crop production and fertilizer manufacture contribute about almost 90%.[3]

There is no doubt that modern agriculture is problematic and it needs to be reviewed and revised. On the flip side, agriculture soil with huge potential for carbon sink is also our ally in the fight against climate change when the right knowledge and appropriate technology are applied. Global soils have the potential to sequester around 20,000 megatonnes of carbon in 25 years, more than 10% of greenhouse gas emission.[4] We could proactively sequester carbon in soil. This is an “immediately available solution” to climate change when we manage soils in an evidence-based and scientific manner.[5] In the Project Drawdown published in 2018, regenerative agriculture ranked 11th among 100 solutions to reverse climate change, and in this solution, it is said “An international movement addressing soil health and carbon sequestration in annual cropping systems is growing. This is extremely timely given agriculture’s current emissions and the great potential for sequestration on croplands.”[6]

The “4 per 1000: soils for food security and climate” Initiative (“4 per 1000” Initiative) started by France in COP21 states clearly that “an annual growth rate of 0.4% in the soil carbon stocks in the first 30-40 cm of soil” would possibly halt the increase of CO2 concentration in the atmosphere.[7] Plants absorb CO2 through photosynthesis to feed the microbes in soil, and when plants die and decompose, soil living organisms transform plants into organic matter, restoring the carbon in soil.

[1] The Food and Agriculture Organization, The Global Soil Organic Carbon Map, retrieved from: http://www.fao.org/global-soil-partnership/pillars-action/1-soil-management/en/

[2] Lal, R., Follett, R. F., Stewart, B. A. & Kimble, J. M. (2007), Soil carbon sequestration to mitigate climate change and advance food security. Soil Sci. Dec. 2007 172, 943–956.

[3] Vermeulen, S. J., Campbell, B. M. & Ingram, J. S. I. (2012), Climate Change and Food Systems. Annu. Rev. Environ. Resour. 37, 195–222.

[4] The Food and Agriculture Organization, “World’s most comprehensive map showing the amount of carbon stocks in the soil launched”, retrieved from: http://www.fao.org/news/story/en/item/1071012/icode/

[5] Rodale Institute, Regenerative Organic Agriculture and Climate Change A Down-to-Earth Solution to Global Warming, retrieved from:

https://rodaleinstitute.org/assets/WhitePaper.pdf

[6] Project Drawdown, retrieved from: https://www.drawdown.org/solutions/food/regenerative-agriculture

[7] 4 per 1000 initiative, What is the “4 per 1000” Initiative?, retrieved from:

https://www.4p1000.org/sites/default/files/content/en-4pour1000-8pages.pdf

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