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Soil Health

How Fertilizers Help Protect
and Capture Soil Organic Carbon

Soil Organic Carbon (SOC) found in the living matter in soils acts as a sink that traps and stores CO2 – a major contributor to global warming.

Soils represent the largest terrestrial pool of carbon: each hectare can store up to 50 – 300 tonnes of carbon1, which is equivalent to 180 – 1,100 tons of CO22.

By increasing crop yields and productivity on available arable land, fertilizers help protect carbon-rich forests, peatlands, wetlands and grasslands by minimizing land use changes.

Increased productivity through fertilizer use has spared 1 billion hectares of virgin land from cultivation between 1961 and 2005 and saved the equivalent of 317 – 590 billion  tonnes of CO2 emissions (the same as total global pre-1800 CO2 emission levels)3.

Soil could store 1.85 billion more tonnes of carbon

With better management, farmland soil could also store up to an extra 1.85 billion tonnes of carbon each year (7 billion tonnes of CO2): around the same amount of CO2 emitted every year by the global transport sector4.

The best way to capture more carbon on farmland is to use fertilizers to optimize plant growth and yields and leave crop residues in the field after harvest.

For every 2 – 3 tonnes of carbon stored above ground in plants,

1 or more tonnes of carbon are generally stored below ground in the roots and root exudates.

Combining mineral and organic fertilizers is the most effective way to increase SOC on arable land. Studies have found this can accumulate up to 2 tonnes of carbon per hectare in a single year5.

Applying fertilizers following the 4R nutrient stewardship principles (using the  Right nutrient source at the Right rate, at the Right time and in Right place) enhances nutrient use efficiency, which reduces nutrient losses to the environment, including in the form of greenhouse gases.

Effective and effcient fertilization is a vital part of the climate-smart agricultural practices that could reduce global emissions by 5.5 to 6 billion tonnes of CO2 equivalent per year: around the same as removing 1,500 coal-fired power plants from the energy sector6.

Capturing carbon in soil organic matter represents 89% of agriculture’s future mitigation potential, with 70% of this happening in low- and middle-income countries7.

To help fight climate change we need to use fertilizers globally to grow more crops on existing farmland to protect carbon stored in wild ecosystems and increase the carbon stored in our agricultural soils.

2 One tonne of carbon equals 44/12 = 11/3 = 3.67 tonnes of carbon dioxide.
3 Burney et al. (2010)
4 Zomer et al. (2017)
5 Yang et al. (2016)
6 Smith et al. (2007)
7 Smith et al. (2007)