Dr Gareth Norton, Dr L Beesley, Prof Graeme Paton, Dr R Hough
No more applications being accepted
Competition Funded PhD Project (European/UK Students Only)
About the Project
Background: The growth of the renewable energy sector has led to the development and installation of efficient biomass boilers, the feed stock for which is normally virgin biomass. In some instances wood from other sources is also used, i.e. waste wood, but the ash generated can be grossly contaminated and unsuitable for soil application. Woody biomass is a renewable source of energy, and as such facilities to generate heat from its use are eligible for government schemes and grants. The by-product of this form of energy generation is wood ash which has a number of very useful applications in agriculture. One of the main benefits is the effect wood ash has on increasing soil pH, therefore the ash can be applied as a useful soil conditioner. Wood ash is also a source of both macro and micronutrients, notably being high in P, K, Ca and Mg. As biomass boilers continue to increase in popularity, there is a need to find a sustainable use for the associated end-product and to ensure a reduction in the volume of ash being landfilled.
Hypothesis- Macro and micronutrients can be extracted from wood ash and utilised as effective soil fertilisers
Project: The major aim of the project will be to assess the potential use of wood ash and extractions of the wood ash, as a suitable source of macro and micronutrients to agricultural soils.
The research will focus on the effect the application of ash and ash extracts have on: 1) the soil chemical (pH, micronutrient availability and CEC), 2) physical (bulk density and water retention, infiltration) and 3) biological properties (microbial biomass / community composition, soil respiration) in the context of the impact of wood ash to soils used for crop production.
Experiments will initially be conducted at pot scales at University of Aberdeen glasshouse/environmental controlled facilities and then up-scaled intelligently to field plot trials at the James Hutton Institute’s experimental farm(s). These experiments will trial the application of wood ash(es) in both solid form and extractions, to soils. Extraction methods will be developed to remove macro and micronutrients from the ashes in the, and parallel trials will compare the effects of solid ash and liquid extracts, as well as assess the value of the remaining ‘spent’ solid ash. Initial extraction techniques will involve water extractions for water soluble nutrients, for example K and acid extraction for nutrients such as P. Extractions will then be concentrated using resin based techniques. The wood ashes used will be based on initial testing of ashes from a variety of commercial and industrial sources and an assessment of their nutrient content versus PTE (potentially toxic elements) composition.
The final stage of the work will be to create a predictive model, based on experimental evidence, to aid the effective deployment of the solid or liquid extract ashes to nutrient poor Scottish soils. The aim of the modelling will be to develop user-friendly tools to predict micro-nutrient value (and potentially yield of crops) from empirical chemical analysis of the ash product and the receiving soil. This modelling will include both beneficial as well as PTEs, and thus indicate under which circumstances different ash types should be excluded from soil application, based broadly on their source origin. For Scottish soils there is potential to link this tool to spatial data resources such as the soils database to develop applications to support farmers in appropriate use of ash as a fertiliser.
Research training value of project: Skills to be developed for the student include: practical glass house and laboratory skills especially in the use of analytical chemistry techniques such as ICP-MS and MP-AES, field trial set-up and management, data gathering, data handling mathematical modelling and statistical analysis including programming/coding; more generic transferable skills such as presentation and writing, teaching and mentoring, and stakeholder interaction.
The student will also benefit from being closely involved with a number of producers of renewable energy both large and small-scale. This will enable the student to gain insight into the industry including gaining a detailed understanding of feedstock and by-product (ash) handling at the different facilities and scales.
Funding Notes
This project is funded by the EASTBIO BBSRC Doctoral Training Partnership. Applications for EASTBIO studentships are invited from excellent UK* students for projects available across our four partner institutions. To be eligible, you must either have or expect to obtain a 1st or a 2.1 undergraduate degree and fulfil the residency criteria. Please check the BBSRC eligibility criteria at http://www.bbsrc.ac.uk/documents/training-grant-faqs-pdf/ (esp. sections 4.1 & 4.2).
References
Gell, K., van Groenigen, J-W., Cayuela, M-L. (2011) Residues of bioenergy production chains as soil amendments: Immediate and temporal phytotoxicity. Journal of Hazardous Material, 186: 2017-2025.
Hough, R.L., Booth, P., Avery, L.M., Rhind, S., Crews, C., Bacon, J., Campbell, C.D. & Tompkins, D. (2012) Risk assessmentof the use of PAS100 green composts in Scottish livestock production. Waste Management, 32:117-130.
Mollon, L.C., Norton, G.J., Trakal, L., Moreno-Jimenez, E., Elouali, F.Z., Hough, R.L., Beesley, L. Mobility and toxicity of heavy metal(loid)s arising from contaminated wood ash application to a pasture grassland soil. Environmental Pollution, in-press A.,