Soil Carbon Sequestration as an Elusive Climate Mitigation Tool

Soil carbon sequestration is a riskier long-term strategy for climate mitigation than direct emissions reduction, but it plays a main role in closing carbon emission gaps. Effects of long-term cultivation on soil carbon sequestration were studied at the western edge of the Nile Delta near Alexandria, Egypt. Seven agricultural fields of different ages (0–50 years in use) were selected and compared with the surrounding desert (virgin soil) and desert shrub-land. Samples were taken at three horizons, 0–30, 30–60, and 60–90 cm, and tested for differences in physical and chemical properties. The results of long-term cultivation reveal that the European Commission (EC) value was 11.77 dS/m in virgin soil, while the EC values decreased to 5.82, 4.23, 3.74, 2.40, and 2.26 dS/m after 5, 10, 20, 30, and 50 years of cultivation, respectively. The calcareous rock fraction smaller than 50 μm in size revealed another phenomenon, where active calcium carbonate content increased with cultivation practices from 1.15% (virgin soil) to 5.42%, 6.47%, 8.38%, and 10.13% after 5, 10, 20, and 30 years of cultivation, respectively, while shrub-land also showed a low amount of active CaCO3 with 1.38%. In fifty years of cultivation, soil bulk density decreased significantly from 1.67 to 1.11 g/cm3, and it decreased to 1.65, 1.44, 1.40, and 1.25 g/cm3 after 5, 10, 20, and 30 years, respectively. These results reveal that the increase in soil carbon stock in the upper 90 cm amounted to 41.02 t C/ha after five years of cultivation, compared to virgin soil with 13.47 t C/ha. Soil carbon levels increased steeply during the five years of cultivation, with an average rate of 8.20 t C/ha per year in the upper 90 cm. After the first five years of cultivation, the carbon sequestration rate slowed, reaching 4.68, 3.77, 2.58, and 1.93 t C/ha per year after 10, 20, 30, and 50 years, respectively, resulting in sequestration-potential values of 46.78, 75.63, 77.43, and 96.45 t C/ha. These results indicate that potential soil carbon sequestration resembles a logarithmic curve until the equilibrium state between carbon application and decomposition by microorganisms is reached.

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Correction for Amundson and Biardeau, Opinion: Soil carbon sequestration is an elusive climate mitigation tool

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1908917116 ◽

2019 ◽

Vol 116 (26) ◽

pp. 13143-13143 ◽

Cited By ~ 1

Keyword(s):

Carbon Sequestration ◽

Soil Carbon ◽

Soil Carbon Sequestration ◽

Climate Mitigation

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Towards a global-scale soil climate mitigation strategy

Nature Communications ◽

10.1038/s41467-020-18887-7 ◽

2020 ◽

Vol 11 (1) ◽

Cited By ~ 2

Author(s):

W. Amelung ◽

D. Bossio ◽

W. de Vries ◽

I. Kögel-Knabner ◽

J. Lehmann ◽

...

Keyword(s):

Carbon Sequestration ◽

Soil Carbon ◽

Global Scale ◽

Soil Carbon Sequestration ◽

Soil Conditions ◽

Climate Mitigation ◽

Management Options ◽

Trade Offs ◽

Local Soil ◽

Carbon Losses

Abstract Sustainable soil carbon sequestration practices need to be rapidly scaled up and implemented to contribute to climate change mitigation. We highlight that the major potential for carbon sequestration is in cropland soils, especially those with large yield gaps and/or large historic soil organic carbon losses. The implementation of soil carbon sequestration measures requires a diverse set of options, each adapted to local soil conditions and management opportunities, and accounting for site-specific trade-offs. We propose the establishment of a soil information system containing localised information on soil group, degradation status, crop yield gap, and the associated carbon-sequestration potentials, as well as the provision of incentives and policies to translate management options into region- and soil-specific practices.

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Potential agricultural soil carbon sequestration across Europe: a reality check

10.5194/egusphere-egu21-9512 ◽

2021 ◽

Author(s):

Leonor Rodrigues ◽

Brieuc Hardy ◽

Bruno Huyghebaert ◽

Jens Leifeld

Keyword(s):

Carbon Sequestration ◽

Soil Carbon ◽

Agricultural Sector ◽

Agricultural Soils ◽

Ghg Emissions ◽

Climatic Conditions ◽

Soil Carbon Sequestration ◽

European Countries ◽

Climate Mitigation ◽

Reality Check

<p>To meet the Paris Agreement goal of limiting average global warming to less than 1.5&#176;C above pre-industrial temperatures, European Union (EU) aims to reduce by 40% its domestic greenhouse gas (GHG) emissions by 2030 and in the longer term to become the world&#8217;s first climate-neutral economy by 2050 (&#8220;Green Deal&#8221;). Today, 10% of the European GHG emissions derive directly from agriculture, and measures to decrease or compensate these emissions are required for achieving climatic goals. The role of soils in the global carbon cycle and the importance of reducing GHG emissions from agriculture has been increasingly acknowledged (IPCC, 2018, EEA report 2019). The &#8220;4 per 1000&#8221; initiative (4p1000) has become a prominent model for mitigating climate change and securing food security through an annual increase in soil organic carbon (SOC) stocks by 0.4 %, or 4&#8240; per year, in the first 0-40 cm of soil. However, the feasibility of the 4p1000 scenario and more generally the capacity of European countries to implement soil carbon sequestration (SCS) measures are highly uncertain.</p><p>As part of the EJP Soil project, we collected country-specific informationonon on the available knowledge and data of achievable carbon sequestration in mineral agricultural soils (cropland and grassland) across Europe, under various farming systems and pedo-climatic conditions. With this bottom-up approach, we provide a reality check on weather European countries are on track in relation to GHG reductions targets and the &#8220;4p1000&#8221; initiative. First results showed that the availability of datasets on SCS is heterogeneous across Europe. While northern Europe and central Europe is relatively well studied, references are lacking for parts of Southern, Southeaster and Western Europe. Further, this stocktake highlighted that the current country-based knowledge and engagement is still poor; very few countries have an idea on their national-wide achievable SCS potential. Nevertheless, national SCS potentials that were estimated for 13 countries support the view that SCS can contribute significantly to climate mitigation, covering from 1 to 28, 5 % of the domestic GHG emissions from the agricultural sector, which underpins the importance of further investigations.</p>

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