Unlocking the potential of SOC for climate action, food security and sustainable

development - a feasible futurePete Smith

Professor of Soils & Global Change, FRSB, FRSE, Institute of Biological & Environmental SciencesUniversity of Aberdeen,Scotland, UK. E-mail: pete.smith@abdn.ac.uk

SOC for climate action

https://ccafs.cgiar.org/http://www.fao.org/home/en/

Climate Smart Agriculture

What does CSA aim to do?• Climate-smart agriculture promotes production

systems that: – Sustainably increase productivity, – Increase resilience (adaptation), – Reduce/remove GHGs (mitigation), and – Enhance achievement of national food security and

development goals.

https://ccafs.cgiar.org/http://www.fao.org/home/en/

www.fao.org/climatechange/climatesmart/en

So where do soils fit it?

Decision tree for enhancing C in croplands

Paustian et al. Nature (2016)

Global potential for agricultural GHG mitigation

Paustian et al. Nature (2016)

Soil C & biochar mitigation potentials

• Biochar (Woolf et al., 2010)– Technical potential = 1.8 Gt Ceq/yr– Potential accounting for competition for non-waste

biomass = 0.7 Gt Ceq/yr• Soil C sequestration (Smith et al., 2008; Smith,

2012)– Technical potential = 1.3 Gt Ceq/yr– Economic potential at 20-100 US$/tCO2eq = 0.4-0.7

Gt Ceq/yr

Smith GCB (2016)

Impact / limit summary for NETS (with biochar and SCS)

Smith GCB (2016)

SOC for food security

Benefits of soil C sequestration

Relative annual change in SOC (0-20 cm) (%)

0 2 4 6 8 10 12 14

Relative annual change in crop productivity (%

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Meta-analysis of 32 papers, reporting 151 relevant comparisons of location, practice, and crops over 4 years or more. Crop species: B, beans; C, cassava; M, maize; P, sweet potatoes; R, rice; S, soybean; s, sorghum; W, wheat. Field experiment regions: Africa (Black); Asia (Green); Latin America (Blue). The solid line is the Standard Major Axis regression for all data points (n=151, Spearman’s rank correlation: y= 0.495 + 3.21 x; r=0.205, P<0.012).

Increasing SOC increases crop productivityFrank et al. (in revision)

Does SOC increase yield or does yield increase SOC?

Hijbeek et al. (2016)

SOC increases yield and yield stability

Pan et al. (2009)

in most eco-climate zones, where the climatic drivers of yield are similar, the provinces with higher SOM also tend to have a statistically higher yield. Causality cannot be firmly attributed as a high yield is associated with higher plant production, potentially higher carbon inputs to the soil and therefore higher levels of SOM over time. Nevertheless, within regions with similar current climatic growing conditions, which should give similar yields if climate is the over-riding factor determining current yield, those provinces with higher SOM tend to have higher yield.

Threats to soils…. SOC to reverse degradation

Smith et al. GCB (2016)

Threats to soils….SOC to reverse degradation

Smith et al. SOIL (2015)

Threats to soils…. SOC to reverse degradation

FAO & ITPS (2015)

“The overwhelming conclusion of the first-ever comprehensive report on the world’s soil resources, prepared by the Intergovernmental Technical Panel on Soils (ITPS), is that the majority of the world’s soil resources are in only fair, poor or very poor condition... and that conditions are getting worse in far more cases than they are improving. Further loss of productive soils will severely damage food production and food security, amplify food price volatility, and potentially plunge millions of people into hunger and poverty.

SOC to help deliver the UN SDGs

The significance of soils and soil science towards realization of the UN sustainable development

goals

Keestra et al. SOIL (2016)

Societal benefits from soil carbon sequestration

Chabbi et al. NCC (in review)

A few caveats….

Smith (2008) International Journal of Agricultural Sustainability 6(3),169–170

Non-permanence / reversibility

Leakage / displacement: are we actually sequestering carbon or just moving it about?

A feasible future: the time of soils has come….

http://www.fao.org/climate-smart-agriculture/en/

http://www.fao.org/globalsoilpartnership/en/

The IYS 2015 aims to increase awareness and understanding of the importance of soil for food security and essential ecosystem functions.

The IYS website is the main platform to share information and relevant resources with different partners.

2015INTERNATIONAL YEAR OF SOILS

http://www.fao.org/globalsoilpartnership/iys-2015/en/

The 4 0/00 initiative

Conclusions• Soils are a vital component of resilient agricultural systems (higher

soil carbon makes soils more resilient)• Soils have a critical role to play in addressing three of the greatest

global challenges: climate change, food security and sustainable development

• The Climate Smart Agriculture and 4 0/00 initiatives can easily be aligned

• The lasting legacy of the UN International Year of Soils in 2015 should be put soils at the centre of policy supporting environmental protection, food security and sustainable development

• Soil scientists must seize the moment, and capitalise on this unprecedented political interest – and help our global, national and regional policy makers to improve soils to improve the planet

Thank you for your attention