2015 has been an exciting year for those of us engaged in research to support sustainable development of agriculture in the tropics. The Sustainable Development Goals have been adopted, and incorporate goals for society, agriculture, and ecosystems, including the agendas of the three Rio Conventions, the United Nations Convention to Combat Desertification (UNCCD), the Convention on Biological Diversity (CBD), and the United Nations Framework Convention on Climate Change (UNFCCC). Especially relevant to UNCCD is the goal that includes achieving a land degradation-neutral world by 2030. At the COP12 of the UNCCD in Ankara, Turkey a Rio Conventions Pavilion hosted various engaging programs, workshops and activities linking biodiversity, climate change and sustainable land management.
During the International Year of Soils 2015, soil organic carbon has taken a place front and center as a complimentary focus for both the UNCCD and the UNFCCC. Soil organic carbon is arguably the crucial important link between land restoration (required to meet land degradation neutrality) and agriculture solutions to climate change adaptation and mitigation (see this video for details). A new initiative led by the French, the 4‰ Initiative: Soils for food security and climate has been introduced. The CGIAR and the French Institutes, INRA, CIRAD and IRD, have recently signed an MoU to collaborate on a large program to implement the 4‰ Initiative in at least five countries. At the Rio Conventions Pavilion I was able to share our thinking on this new climate smart agriculture for food security initiative that bridges the goals of the Rio Conventions by focusing strongly on soil carbon.
It helps to understand three numbers
0.4% per year is the rate of carbon sequestration in soil required to meet the climate change mitigation objectives of the initiative. In March of 2015 Minister Le Foll of France announced the establishment of an international research program “to improve soil organic matter at an annual rate of 4‰1”, and that “such an increase would offset emissions of green house gasses on the planet2” The scale of the soil carbon stock is 1500 billion tons of carbon and at least twice as large as the carbon in CO2 in the atmosphere. The rate is based on the logic that it would be possible to offset all fossil carbon emissions by doubling the current land sink for CO2. To do so through soil carbon sequestration would only require an increase of soil organic carbon of 0.4% per year.
3.5 Gigaton (Gt) per year is the amount of carbon sequestration required to meet the 4‰ target. It is estimated that 0.4 – 1.2 Gt carbon sequestration can be achieved in croplands around the world. To realistically get closer to the goal, it is necessary to include pasture, grasslands, forests and peatlands among other land uses. If we include a wider range of land uses, estimates are it would be possible to sequester an estimated 2.8 to 3.0 Gt of carbon (Lal 2010). It is essential to acknowledge in this discussion that individual soils have a finite capacity to store carbon, and when ecological limits are reached no further sequestration is likely with common practices. If soil carbon sequestration is adopted as a partial solution to mitigate climate change, the greatest impact may be within about 15 years after initiating aggressive soil carbon building interventions, and thereafter decline (Sommer and Bossio 2014). Given the importance of early action, this time frame does not diminish the relevance of soil carbon storage as part of the set of solutions to climate change.
50 to 70
50 to 70% is the magnitude of the loss of carbon stocks from cultivated soils worldwide (Lal 2004). This means that degraded cultivated soils have 50% to 70% of their current carbon sink empty. These are clear areas for immediate attention because environmental factors are less likely to inhibit soil carbon building. When these degraded soils are restored the added carbon will have direct and immediate benefits through increased food production.What are the opportunities?Although the data is scarce, especially in the tropics, there is evidence that some agricultural management systems have significant potential to sequester carbon in soils. These include agroecological systems that focus on internal recycling, crop rotations and building soil organic matter and soil fertility, as well as contribute to climate change adaptation and food security – thus satisfying the three pillars of climate smart agriculture.These examples include:
- Improved forages to increase fodder production in degraded pasture systems, which not only contributes to increased animal production and thus food security and increased resilience to drought, it also can increase soil carbon at depth, where it is more likely to be permanent
- Evergreen agriculture incorporating more trees and farmer assisted regeneration of trees in farming systems, which has been shown to increase food production, climate resilience and landscape carbon in the Sahel
- Well managed irrigation with appropriate soil and crop management, especially involving components of perennial cropping, such as fodders and legumes, have significant potential to increase soil organic matter, even over natural conditions. This is especially important in ecosystems where water is most limiting to biomass production, and in the context of national plans for massive expansion of irrigation infrastructure in Africa.
- Recycling of nutrients from towns and cities back to agricultural lands. Megacities, and more importantly medium and small cities are rapidly growing, and already more than 15% of our agricultural lands lie within 20km of these growing cities. This proximity to huge sources of nutrients that are currently in waste streams, offers many new opportunities to closing nutrient cycles and provide nutrients for biomass production and soil carbon storage.
Unlike engineering solutions in the energy sector, agricultural solutions such as these require strong context specificity. Climate smart agriculture practices that build soil organic carbon will be climate smart in many places, but they will not be climate smart in all places. There are often trade-offs that need to be considered and addressed. Improved knowledge about the suitability of practices to different places and monitoring of implemented projects will inform national policy, extension groups and investors about best practices.Nevertheless, the opportunities are so compelling that despite caution amongst Soil Scientists regarding the realism of the targets and possible trade-offs, at the recent Wageningen Soil Congress it was Agreed that: Increasing soil organic carbon will generally enhance soil life and promote soil functioning with respect to the challenges of food security, water resources, climate change and biodiversity.
And participants/soil scientists therefore agreed to: Initiate and strongly support programs that aim at a lasting increase in soil organic carbon.Soils will be the bridge from the recent UNCCD COP 12 discussions to the upcoming UNFCCC COP21 we are all looking forward to. There, the 4‰ Initiative will be officially launched and soil carbon will feature in a voluntary action plan under the Lima-Paris Agenda for Action.
1 Press release ‘Contribution de l’agriculture à la lutte contre le changement climatique : Stéphane Le Foll annonce le lancement d’un projet de recherche international : le « 4 pour 1000 » . MAAF, Paris, March 17, 2015.2 See https://agriculture.gouv.fr/Cop21-le-4-pour-1000
- Blanco-Canqui, H, & Lal, R. 2009. Crop residue removal impacts on soil productivity and environmental quality. Critical reviews in plant science, 28(3), 139-163.
- Entry, JA, Sojka, RE, Shewmaker, GE. 2002. Management of Irrigated Agriculture to Increase Organic Carbon Storage in Soils. Soil Sci. Soc. Am. J. 66:1957–1964.
- Fisher, MJ; Braz, SP; Dos Santos, RSM; Urquiaga, S; Alves, BJR; and Boddey, RM. 2007. Another dimension to grazing systems: Soil carbon. Tropical Grasslands (2007) Volume 41, 65–83
- Lal, R. 2004. Soil carbon sequestration impacts on global climate change and food security, Science. 304, 1623–1627.
- Lal, R. 2006. Enhancing crop yields in the developing countries through restoration of the soil organic carbon pool in agricultural lands. Land Degradation & Development, 17(2), 197-209.
- Lal, R. 2010. Managing soils and ecosystems for mitigating anthropogenic carbon emissions and advancing global food security. BioScience. 60.9: 708-721.
- Sommer, R, Bossio, D. 2014. Dynamics and climate mitigation potential of soil organic carbon sequestration. Journal of Environmental Management. Vol 144, 83-87. DOI: 10.1016/j.jenvman.2014.05.017
- Soussana, JF, Saint-Macary, H., Chotte, J-L., Bellassen, V., Toillier, A. 2015. Carbon sequestration in soils. Towards an international ‘4 per mil’ research program and action plan. Scientific Concept Note, Side Event: ‘Carbon sequestration in soils: a challenge for food security and climate action’, 7 July 2015, UNESCO ‘Our Common Future under Climate Change’.
- Thebo, AL, Drechsel P, Lambin, EF. 2014 Global assessment of urban and peri-urban agriculture: irrigated and rainfed croplands. Environ. Res. Lett. 9 114002 doi:10.1088/1748-9326/9/11/114002
The UN has declared 2015 as the International Year of Soils to raise awareness of the urgent need to protect the resource that feeds and waters us. Find out how CIATs global soils research team of soil scientists, ecologists and anthropologists are working with partners to protect and restore this vital resource.