Understanding how native legume trees can help maintain pasture productivity and prevent agricultural expansion into the Amazon, Geography – PhD (Funded) Ref: 4665

About the award


Prof Toby Pennington, University of Exeter

Dr Alexandre de Azevedo Olival, UNEMAT

Dr Lucy Rowland, University of Exeter

Dr Fernanda Barros, University of Exeter


Geography, Streatham Campus, Exeter

The University of Exeter’s Department of Geography is inviting applications for a PhD studentship fully-funded by Shell to commence on 25 September 2023 or as soon as possible thereafter.  For eligible students the studentship will cover international tuition fees plus an annual tax-free stipend of at least £17,668 for 3.5 years full-time, or pro rata for part-time study.

The student would be based in Geography at the Streatham Campus in Exeter, but will also spend significant time in the field working with partners in Brazil.


Pastures account for 21.5% of Brazil’s 8.5 million km2 territory. However, 54% of these are moderately or severely degraded and only being used to support very few animals, thus producing limited economic output, whilst also having very limited biodiversity and carbon storage value. This continued degradation is one of the primary drivers of continued agricultural expansion into the Amazon rainforest. However, across Brazil there is evidence that many farmers are choosing to leave native plants within pasture systems, as evidence suggests that this can increase the productivity of the system, alongside providing shade for animals and alternative incomes from fruit and nut products.

Our key research partner, Instituto Ouro Verde, also has a track record for enabling local farmers to lower costs and increase pasture productivity using native tree species. However, evidence for how native tropical trees may be increasing productivity in pastures is limited and often only anecdotal.

One of the key categories of native trees which are being planted and maintained in Amazonian pastures are legumes. Legumes are well known for being able to increase the fertility of soils because many of them have the ability to fix atmospheric nitrogen via a symbiosis in nodules in their roots. However, we lack good comparisons of the relative benefits to pasture soils of legume versus non-legume trees.  In addition, in the face of thousands of legume tree species in Latin America, we need to understand more about the effectiveness of different legume species to increase pasture productivity, how this is influenced by planting densities in pastures and if nitrogen fixation varies depending on the age of the tree.


The aim of this PhD is to work with a Shell funded research project Carbon Storage in Pasture through Ecological Restoration (CASPER), focusing on how legume trees can improve pasture productivity and carbon storage within pastures being actively managed in Mato Grosso by our local collaborators Instituto Ouro Verde. Specifically, this PhD aims to evaluate

1) How the identity and density of legume tree species alters pasture productivity

2) How soil-plant interactions change with nodulating, non-nodulating and non-legume tree species in pastures

3) If the age of the legume trees impacts their capacity to increase pasture productivity and carbon storage

Addressing these aims will involve undertaking repeat measurements of plant and soil physical and chemical properties, alongside understanding the taxonomy and phylogeny of the legumes which exist across pasture systems in the Amazon. However, the broader project will involve this student engaging with the ecological, economic and social contexts of both native and pasture restoration across Brazil.


The project requires a multidisciplinary approach, and the student will receive training on undertaking plant and soil chemical analysis. Day-to-day monitoring and maintenance of the sites will be undertaken by in-country partners, within whom this PhD student will work very closely. This research will be conducted as part of a wider research program that investigates sustainable routes for maximising carbon sequestration and biodiversity from restoring pastures in Brazil.

This award covers home or international tuition fees and a tax-free stipend and international applicants will have visa costs, the healthcare surcharge and the travel costs of moving to the UK covered. Additional funding is available to assist with the cost of international students moving to the UK.

Entry requirements

Applicants for this studentship must have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK, in an appropriate area of science or technology. 

Language tests do not need to be undertaken prior to application, only post-offer. Furthermore, the applicant must speak both Portuguese, as all fieldwork and activities within the partner organisation UNICAMP must be conducted in Portuguese (both spoken and written).

How to apply

In the application process you will be asked to upload several documents.

• CV

• Letter of application (outlining your academic interests, prior research experience and reasons for wishing to undertake the project).

• Transcript(s) giving full details of subjects studied and grades/marks obtained (this should be an interim transcript if you are still studying)

• Names of two referees familiar with your academic work. You are not required to obtain references yourself. We will request references directly from your referees if you are shortlisted.

• If you are not a national of a majority English-speaking country you will need to submit evidence of your proficiency in English.

The closing date for applications is midnight on Monday 13th February 2023 GMT.

Interviews will be held virtually / on the University of Exeter Streatham Campus in March 2023.

If you have any general enquiries about the application process please email pgrenquiries@exeter.ac.uk or phone 0300 555 60 60 (UK callers) +44 (0) 1392 725150 (International callers). 

Project-specific queries should be directed to the main supervisor.


Application deadline:13th February 2023
Value:The studentship will cover international tuition fees plus an annual tax-free stipend of at least £17,668 for 3.5 years full-time, or pro rata for part-time study.
Duration of award:per year
Contact: PGR Admissions Teampgrenquiries@exeter.ac.uk


Leave a Reply

%d bloggers like this: