Soil Carbon Sequestration – Offsetting Greenhouse Gases

Global Change Biology 2021;00:1–18

Together with project partners, Agroscope investigated soil carbon sequestration potentials for 24 European countries. Carbon sequestration could offset 0.1% to 27% of greenhouse-gas emissions from agriculture per annum.

Greenhouse gases can only by reduced through a package of measures. Using data from the literature and together with project partners, Agroscope researchers investigated one aspect of this issue as part of the EU project EJP SOIL. This led to the paper Achievable agricultural soil carbon sequestration across Europe from country-specific estimates, published in the scientifically peer-reviewed journal Global Change Biology. The paper discusses increasing soil carbon sequestration to offset agricultural greenhouse-gas emissions. It was shown that each country can only achieve this aim through country-specific measures. This is because the situation differs in every country: soils vary in terms of carbon content and management system, and thus require different measures for achieving the target. According to current national estimates, 0.1 to 27% of greenhouse-gas emissions from agriculture could be offset by additional carbon sequestration in agricultural soils.

Biochar could help in Switzerland

France, for example, could achieve good results with agroforestry systems; Belgium, for its part, would benefit most from arable crops for bioenergy generation; and for Switzerland and Norway, the authors show that the use of biochar or deep-ploughing could be possible options. Deep-ploughing is a problematic approach, since it can cause irreversible damage to the soil. Biochar, however, is not only highly stable, but its use has further benefits, including the fact that no additional nitrogen is needed in order to sequester the carbon in the soil. This means that the use of biochar also reduces nitrogen emissions.

Nevertheless, further research is needed to determine the requirements for the successful use of biochar as well as its potential risks for soil health. Furthermore, it is difficult to validate success, since the effects of changing management systems are only measurable in the soil after fairly long periods of time.

4p1000 Initiative not achievable

The 4p1000 Initiative was launched to achieve precisely that aim: to continuously store carbon in the soil. The Initiative proposes increasing the carbon content in the top 40 cm of the soil by 0.4% per annum. Estimates produced by Agroscope and its project partners suggest that this aim is unachievable with the measures proposed nationally to date – the countries examined are only achieving values of between 0.003% and 0.28%.