Supervisors: Dr Jon Hillier, Professor Pete Smith
Project Description:
The recent 4-per-1000 initiative and the adoption of science-based targets by many businesses has led to renewed interest in the potential of SOC to both reduce net global emissions of carbon and to improve food security.
The “4-per-1000 Initiative: Soils for Food Security and Climate”, resulted from COP 21, and is supported by 39 countries and more than 190 organizations as of June 2017. This initiative sets a global aspirational goal to increase SOC stock at an annual rate of 0.4% per year in all land uses. If, this target would double the total mitigation encompassed by the COP21 Nationally Determined Contributions (NDCs), compared to the baseline scenario of the fifth assessment report of the IPCC.
Recent studies have explored the feasibility of this plan and the potential benefits in respect of food security. Soussana et al (2017) estimated the potential impact of a 0.4% increase in SOC using 32 studies in developing countries. They concluded a correlation, albeit with substantial scatter, in which an increase in grain yield of 1.3% is associated with a 0.4% increase in SOC stocks. Frank et al (2017) further assert that, with many of the gains occurring in developing countries such an increase can reduce the calorie deficit in these countries by around 100 calories per person per day.
The potential for improving SOC stocks to contribute significantly to food security, is further supported by the co-benefits of SOC on soil physical functions, such as water holding capacity (meaning reduced leaching of N), and biological functions through increased organic material which additionally confer resilience. Although the mechanistic basis for the beneficial effects of increased SOC stocks is clear, the strength of the relationship between SOC and crop yield is not well established at field level. Yue et al (2018), for example, using data from China found no significant direct effect of SOC on yield, but a significant effect of soil clay content which is associated with SOC holding capacity.
We propose a modelling based project to establish the potential of SOC to affect future food production. This will have three main research themes/questions informed by an initial literature review.
0. Meta-analysis to explore the impact of achieving science based (e.g. 4-per-1000) targets for SOC enhancement on yield and soil performance for major global cereal and commodity crops
1. Quantify the effect of SOC on soil “performance” – the physical and biological functions of soil and the conferred crop resilience.
2. Development of practical metrics for use at scale by non-experts to predict soil “performance” as a function of SOC – embedding in the Cool Farm Tool.
3. Model, using future scenarios consistent with it, the impact of 4-per-1000 increase in SOC on global food production in 2030 and 2050.
The student will receive training in statistical meta-analysis, mixed-effects modelling, and process-based soil carbon modelling, in addition to spending time working with the Cool Farm Alliance in identifying the translation requirements of its membership and to embed new soil performance metrics in the Cool Farm Tool.
References:
Frank, S.et al. 2017. Reducing greenhouse gas emissions in agriculture without compromising food security? Environmental Research Letters 12, 105004.
Soussana, J.-F. et al. 2018. Matching policy and science: rationale for the ‘4 per 1000 soils for food security and climate initiative. Soil & Tillage Research (online). doi: 10.1016/j.still.2017.12.002.
Yue, Q. et al. 2018. Re-assessing Nitrous Oxide Emissions from Croplands Across Mainland China, submitted to Agriculture, Ecosystems and Environment
If you wish to apply for this project, please check this link and send your application to this email.
