Elsevier

Global Environmental Change

Volume 35, November 2015, Pages 269-278
Global Environmental Change

The dynamic soil organic carbon mitigation potential of European cropland

https://doi.org/10.1016/j.gloenvcha.2015.08.004Get rights and content

Abstract

Changes in soil organic carbon stocks depend on the management regime and a variety of environmental factors including climatic conditions and soil properties. So far, the dynamics of soil organic carbon have not been explicitly represented in global economic land use optimization models. Here, we apply an approach to represent soil organic carbon dynamics explicitly in a global bottom-up recursive dynamic partial equilibrium model using carbon response functions simulated with a biophysical process-based model. We project soil organic carbon emissions from European cropland to decrease by 40% from 64 MtCO2 in 2010 to about 39 MtCO2 in 2050 mainly due to saturation effect when soils converge toward their equilibrium after management, crop rotation, or land use change. Moreover, we estimate a soil organic carbon mitigation potential for European cropland between 9 and 38 MtCO2 per year until 2050 for carbon prices between 10 and 100 USD/tCO2. The total European mitigation potential including co-benefits from the crop and livestock sector due to the carbon price is even higher with 60 MtCO2 equivalents (eq) per year. Thus carbon sequestration in soils could compensate 7% of total emissions from agriculture within the EU, 10% when including co-benefits from the crop and livestock sector. However, as production is reallocated outside Europe with increasing carbon prices, emissions decrease in Europe but increase in the rest of the world (20 MtCO2 eq). Preventing GHG emission leakage to the rest of the world would decrease the European soil organic carbon mitigation potential by around 9% and the total European mitigation potential including co-benefits by 16%. Nevertheless, the net global mitigation potential would still increase. We conclude that no significant contributions to emission reduction targets should be expected from the European cropland carbon sequestration options considered in this study.

Introduction

World soils are the third largest global carbon stock behind the oceanic and the geologic carbon pool. They contain about twice as much organic carbon as the atmosphere and thrice as much as biomass (Powlson et al., 2011b, Smith, 2012b). Soils can be a major source or sink of carbon dioxide (CO2) emissions depending on the land use and management regime. It has been estimated that agricultural ecosystems have lost 25–75% of their original soil organic carbon (SOC) pool due to the conversion of natural to agricultural ecosystems and other soil degradation processes such as erosion, salinization, and nutrient depletion (Lal, 2011). Improved management of agricultural land has the potential to both reduce net greenhouse gas (GHG) emissions and to serve as a direct carbon sink through SOC sequestration. Management practices such as reduced and minimum tillage, improved residue management and crop rotations as well as the conversion of marginal cropland to native vegetation or conversion of cultivated land to permanent grassland offer the potential to increase SOC stocks (IPCC, 2007). However, sequestration rates do not only depend on the management regime but also on environmental factors including climatic conditions and soil properties (Bellamy et al., 2005). Depending on the history of land management, different management systems may either sequester carbon in the soil or cause emissions (West et al., 2004). Moreover, SOC stocks usually increase as mean annual temperature decreases, and rainfall and clay content increase due to reduced decomposition rates (Post et al., 1982, Powlson et al., 2011a).

While the dynamic interactions between SOC sequestration rates and soil management are widely acknowledged in literature, they have not been considered in most existing economic land use models. A major obstacle is the high data and computing requirements for an explicit representation of alternative land use sequences since a model has to be able to track all different management choices and paths (Schneider, 2007). Several studies estimated SOC emissions from arable land and mitigation potential at regional and global level using either biophysical SOC models in combination with current land use or projections of land use and land use change (Lugato et al., 2014, Smith et al., 2005a, Vleeshouwers and Verhagen, 2002, Yu et al., 2013, Zaehle et al., 2007) or land use models with static SOC sequestration rates (De Cara and Jayet, 2006, Schulp et al., 2008, Thomson et al., 2008). Most studies conclude that European SOC mitigation potential could contribute significantly in reaching emissions saving targets even though estimates have been revised downward (Smith et al., 2005b).

While the technical potential (full adoption given biophysical constraints) of conservation tillage may be large (0.37–0.92 tCO2/ha and year, see Aertsens et al. (2013) and Vleeshouwers and Verhagen (2002)), economic mitigation (adoption under a given carbon price) potentials are often smaller. Freibauer et al. (2004) identify the carbon sequestration potential for the EU15 to be around 59–70 MtCO2 per year with the most promising measures being improved cropland and grassland management (e.g. increased organic matter input, reduced tillage). De Cara and Jayet (2006) quantify the economic mitigation potential of conservation tillage in EU15 to be around 8 MtCO2 at a carbon price of 20 Euro/tCO2 (27 MtCO2 with 100 Euro/tCO2). Recently, the PICCMAT project (Piccmat, 2008) estimated the carbon mitigation potential for reduced and minimum tillage of around 10 and 20 MtCO2 respectively for EU27.

Despite the variety of studies, large uncertainties in the magnitude of SOC emissions and mitigation potential prevail. Recent studies questioned the feasibility to achieve high emission savings through soil organic carbon sequestration (Powlson et al., 2011b). Uncertainties can be attributed to gaps in the understanding of future land use change, quantification of the response of carbon sequestration to land use change (Schulp et al., 2008), future level of adoption of mitigation measures, potential feedback on N2O and CH4 emissions, and persistence of mitigation (Smith, 2012b). In addition, there is an ongoing debate about the “genuinely” positive effect of conservation tillage on SOC sequestration and consequently climate change mitigation since most existing studies relied on shallow sampling depth when comparing sequestration rates of conservation and conventional tillage systems. Some studies conclude that even though conservation tillage may increase surface SOC concentrations, it does not store more SOC in the overall soil profile but solely redistributes carbon in the soil (Baker et al., 2007, Luo et al., 2010).

Besides biophysical uncertainties also economic effects such as GHG emission leakage need to be considered to guarantee effectiveness of GHG mitigation options and climate change policies (Ostwald and Henders, 2014). In the European Union (EU), CO2 emissions from agriculture, forestry and other land use have not been included in the emissions reduction targets so far besides the CO2 emissions due to energy use. This is under discussion in the forthcoming energy and climate mitigation policy framework for 2030 to ensure cost-effective GHG abatement across sectors (EC, 2014). However, applying a mitigation policy only at regional scale may result in emission leakage to regions not adopting the mitigation policy (IPCC, 2000). Indirect effects such as conversion of native vegetation elsewhere to agriculture in order to compensate for agricultural production losses (e.g. through switch to perennial crops for biofuel production or decreased productivity related to the adoption of conservation tillage) could therefore negate the benefits of carbon sequestration through increases in GHG emissions in other sectors or regions (Powlson et al., 2011b, Smith, 2012b).

To reduce uncertainty and provide theoretically and empirically more consistent estimates of the European SOC mitigation potential from cropland, a framework is needed capable of representing biophysical SOC dynamics as well as the land use and land use change sector including its economic drivers and feedbacks to and from other sectors. Hence, we implement a dynamic SOC modeling approach introduced by Schneider (2007) and applied so far only in a case study region (Freier et al., 2011) into GLOBIOM-EU, a global bottom-up partial equilibrium model based on GLOBIOM (Global Biosphere Management Model) (Havlík et al., 2014). We estimate SOC emissions from cropland in the EU until 2050. Then we assess the dynamic European cropland SOC mitigation potential by implementing a carbon price in the model. By mimicking a policy implementation in Europe only, we assess potential GHG emission leakage effects in the rest of the world (ROW). In addition, we explore the impact of preventing emission leakage on the European SOC mitigation potential.

Section snippets

Methodology

We use GLOBIOM-EU, a partial equilibrium land use model based on GLOBIOM (Havlík et al., 2014). GLOBIOM-EU and GLOBIOM are identical regarding data sets and modeling approach for regions outside Europe. Inside Europe, GLOBIOM-EU has been refined to allow for a more detailed representation of the EU28 member countries. Here we provide details about the model in general, spatial resolution, data sources, and the improved crop sector representation in Europe. Moreover, we describe the

Results and discussion

In the first part of the result section we present European SOC emissions from cropland management in our baseline scenario (EU25, without Croatia, Cyprus, and Malta). SOC emissions include emissions from cropland and from conversion of grassland and other natural vegetation to cropland. In the second part, we calculate average sequestration gains of different tillage systems under 100% adoption. We quantify the economic SOC mitigation potential from cropland considering also potential

Conclusion

We conclude that SOC emissions from European cropland management can be reduced and mitigate around 40 MtCO2 eq globally. However, given the prevailing uncertainties, SOC sequestration should not be the only sector being targeted as an over-emphasis may detract from other measures that are at least as effective in mitigation climate change (Powlson et al., 2011b). Globally, reducing emissions from deforestation (Böttcher et al., 2013, IPCC, 2007), increasing nitrogen use efficiency and thus

Acknowledgements

This research has been financially supported by the Austrian Climate Research Program through the CC2BBE (Vulnerability of a bio-based economy to global climate change impacts) project and by the European Commission—DG Climate Action through the tender contract ‘Development and application of EU economy-wide climate change mitigation modelling capacity (all greenhouse gas emissions and removals)’, contract ref no. 071303/2011/600928/SER/CL1MA.A.4.

References (62)

  • A. Popp et al.

    Food consumption, diet shifts and associated non-CO2 greenhouse gases from agricultural production

    Global Environ. Change

    (2010)
  • D.S. Powlson et al.

    Soil management in relation to sustainable agriculture and ecosystem services

    Food Policy

    (2011)
  • V. Sánchez-Girón et al.

    Economics of reduced tillage for cereal and legume production on rainfed farm enterprises of different sizes in semiarid conditions

    Soil Tillage Res.

    (2007)
  • U.A. Schneider

    Soil organic carbon changes in dynamic land use decision models

    Agric. Ecosyst. Environ.

    (2007)
  • U.A. Schneider et al.

    Agricultural sector analysis on greenhouse gas mitigation in US agriculture and forestry

    Agric. Syst.

    (2007)
  • M. Schönhart et al.

    CropRota—a crop rotation model to support integrated land use assessments

    Eur. J. Agron.

    (2011)
  • C.J.E. Schulp et al.

    Future carbon sequestration in Europe—Effects of land use change

    Agric. Ecosyst. Environ.

    (2008)
  • P. Smith

    Agricultural greenhouse gas mitigation potential globally, in Europe and in the UK: what have we learnt in the last 20 years?

    Global Change Biol.

    (2012)
  • P. Smith

    Soils and climate change

    Curr. Opin. Environ. Sustainability

    (2012)
  • A.M. Thomson et al.

    Integrated estimates of global terrestrial carbon sequestration

    Global Environ. Change

    (2008)
  • G. Verch et al.

    Comparing the profitability of tillage methods in Northeast Germany—a field trial from 2002 to 2005

    Soil Tillage Res.

    (2009)
  • S.H. Villarino et al.

    Agricultural impact on soil organic carbon content: testing the IPCC carbon accounting method for evaluations at county scale

    Agric. Ecosyst. Environ.

    (2014)
  • Y. Yu et al.

    Projected changes in soil organic carbon stocks of China’s croplands under different agricultural managements, 2011–2050

    Agric. Ecosys. Environ.

    (2013)
  • J. Balkovic et al.

    D2100 of the cc-tame project: database and data strategy report

    Tech. Rep.

    (2009)
  • Bauer, J., Kniivilä, M., Schmithüsen, F., (2004). Forest legislation in Europe: How 23 countries approach the...
  • P.H. Bellamy et al.

    Carbon losses from all soils across England and Wales 1978–2003

    Nature

    (2005)
  • H. Böttcher et al.

    Future GHG emissions more efficiently controlled by land-use policies than by bioenergy sustainability criteria

    Biofuels Bioprod. Biorefin.

    (2013)
  • De Cara, S., Jayet, P.-A., (2006). Mitigation of greenhouse gas emissions in EU agriculture: An assessment of the costs...
  • EC, (2013). EU Energy, Transport and GHG Emissions Trends to 2050: Reference Scenario 2013. European Commission...
  • EC, (2014). A policy framework for climate and energy in the period from 2020 to 2030. Communication from the...
  • S. Gervois et al.

    Carbon and water balance of European croplands throughout the 20th century

    Global Biogeochem. Cycles

    (2008)
  • Cited by (28)

    • A marginal abatement cost curve for climate change mitigation by additional carbon storage in French agricultural land

      2023, Journal of Cleaner Production
      Citation Excerpt :

      Several studies have estimated the cost-efficiency of carbon storage practices in soils. Most of these studies focused on no-till or reduced tillage (De Cara and Jayet, 2006, Pautsch et al., 2001, Feng et al., 2000, 2002, 2006 and Kurkalova et al., 2006; Moran et al., 2011, Frank et al., 2015), whereas these practices have recently been demonstrated to have little to no effect on soil organic carbon (SOC) stocks in temperate regions when the entire soil profile is considered (Haddaway et al., 2017). Other studies have estimated the cost of storing more SOC by introducing temporary grasslands or alfalfa in typical Australian farms (Kragt et al., 2012), converting arable land to permanent grasslands in some US states (Antle and Capalbo, 2001), or reducing summer fallow and increasing adoption of conservation tillage in US wheat and corn systems (Antle et al., 2007).

    • Responses of soil respiration and C sequestration efficiency to biochar amendment in maize field of Northeast China

      2022, Soil and Tillage Research
      Citation Excerpt :

      Even minor changes in soil C pool can have a substantial influence on atmospheric CO2 concentration (Lal, 2004). Soil organic matter (SOM), the heterogeneous mixture of organic debris formed by plant, animal, and microbial C at various stages of decomposition, is essential for microbial growth, water retention, soil nutrient maintenance, and long-term agricultural sustainability (Chen et al., 2019; Frank et al., 2015). The storage and stability of SOM are extraordinarily noteworthy in the current era plagued by climate change and other environmental challenges.

    View all citing articles on Scopus
    View full text