PhD Studentship: Wildflower Interventions to Boost the Environmental Sustainability of British Hop Production

Closing date: 10 November 2024

Interview date: 21 November 2024

Start date: 20 January 2025

The project

Applications are invited for this full-time PhD studentship, which for UK home students is fully funded* by the Worshipful Company of Brewers, Asahi, Sainsbury’s, and the Royal Agricultural University.

Background

We are amid climate and biodiversity emergencies exacerbated by the need to produce more food to feed a growing population. As part of the approach towards sustainable food production, the UK is aiming to achieve net zero for agriculture by 2040 (NFU). Whilst this is a challenging goal, it presents numerous opportunities for farmers and land managers to not only directly reduce greenhouse gas emissions, but engage with actions that will result in greater carbon storage, reduce their reliance on Plant Protection Products (PPPs), and benefit wider biodiversity. There is clearly an urgent need to develop more sustainable and therefore more resilient approaches to food production in the UK.

However, British hop growers remain highly concerned about Verticillium Wilt (VW), and the potential for hop yields to be impacted through competition from vegetation growing in alleyways between rows of bines. Growers therefore maintain alleyways devoid of vegetation with cultivation and/or herbicides. Unfortunately, bare soil impacts soil health (Mann et al. 2019), whilst regular cultivation releases soil carbon (Yang et al., 2015), and promotes soil erosion (Zízala et al., 2021). It also impacts wider biodiversity (Gillison et al., 2016), and is associated with a poor-quality habitat for natural enemies that could otherwise support production (Aguilar-Fenollosa et al., 2011). Consequently, the sector is failing to contribute to addressing the climate and biodiversity emergencies.

In contrast to bare soil, wildflower interventions provide numerous benefits. These include the greater accumulation of soil organic matter (De Deyn et al., 2011), an increase in soil microbial activity (Canali et al., 2009), and an increase in nutrient cycling (De Deyn et al., 2011), which in turn increases the availability of nutrients to adjacent crops (Canali et al., 2009; Sharifi et al., 2016). Greater amounts of soil organic matter in the alleyways of hop yards might also be expected to buffer against short term drought by increasing the water-holding capacity of the soil (Wolfe et al., 2018), reducing the incidence of water stress (Lepsch et al., 2019). Wildflower strips also deliver important ecosystem services that underpin production, including pest regulation (Albrecht et al., 2020). This could lead to a reduction in the use of PPPs (Mateos-Fierro et al., 2021). They also support wider biodiversity (Hicks et al., 2016).

It is evident that the issues of alleyway vegetation increasing the incidence of VW and providing competition for resources with bines must be investigated enabling the sector to proceed in a more sustainable way. In addition, there also remains the possibility that the introduction of wildflowers could increase VW as some Verticillium spp. have a wide host range and could infect non-hosts asymptomatically and enhance pathogen survival. A rigorous screening programme to determine a suite of perennial wildflower species that can be successfully established in hop gardens/yards without increasing the risk of VW is needed. To minimise the potential issue of increased competition of wildflower interventions with bines there is also a need to investigate the highly novel approach of maintaining wildflower interventions at a height of 20 cm through cutting (Mateos-Fierro et al., 2021). Such an approach has been demonstrated to be highly effective in cherry orchards, which resulted in greater pest regulation in the adjacent cherry trees (Mateos-Fierro et al., 2021) and a greater abundance and diversity of pollinators (Mateos-Fierro et al., 2023).

There are only 45 hop growers remaining in the UK, and the hops they produce are highly sought after, enabling producers to differentiate their beers using unique flavours and aromas. To help underpin this sector there is a need to support hop growers with research that will enable them to increase the resilience and viability of their businesses, whilst enabling them to meet sustainability goals.

The use of wildflower interventions in alleyways between rows of bines is likely to be a game changer for the sector. For the first time, this project will allow the benefits of establishing wildflower strips in hop gardens/yards to be fully investigated.

Over a three-year period, the overall aim of the study is to investigate the benefits of wildflower interventions to support hop production through improved soil health and carbon storage, enhanced pest regulation, and benefits for wider biodiversity. This will be achieved through the following objectives:

1. Through an in-depth literature review and glasshouse-based screening experiment identify perennial wildflower species that can be successfully established in British hop yards without increasing the incidence of Verticillium Wilt.
2. Establish bespoke perennial wildflower strips in British hop yards and investigate the benefits/impacts on the performance of hop bines.
3. Determine the efficacy of perennial wildflower strips to support natural enemies in British hop yards for the control of a range of key pests (aphids and spider mite).
4. Investigate the role of perennial wildflower strips in supporting wider indicators of biodiversity in British hop yards.
5. Determine the potential for perennial wildflower strips to increase soil health with a focus on carbon storage in the alleyways of British hop yards, and their contribution to net zero farming.

Indicative methodology

Following an in-depth literature review, a screening programme wildflower species will be conducted under controlled conditions to identify a suite of species that could be used in hop yards without increasing the incidence of Verticillium Wilt (VW). This information will inform the development of a bespoke seed mix that will be established in British hop yards. The screening programme will take place at the University of Warwick who have expertise working with soil-borne fungal pathogens. The University of Warwick has state-of-the-art climate-controlled glasshouses with a Defra licence to work with VW.

Working with the British Hop Association and Charles Faram & Co Ltd, field sites will be selected for study in Gloucestershire, Herefordshire, and Worcestershire. At each site two plots spatially separated for independence will be selected controlling for factors such as hop variety, age etc. One plot will be managed conventionally with alleyways being maintained void of any vegetation (bare), and one will receive the wildflower interventions.

Hop yields will be compared between treatments to investigate whether the presence of wildflower strips impact productivity due to the possible competition between alleyway vegetation and the hop bines for resources.

The botanical composition of alleyways will be assessed annually to provide an indication of wildflower establishment success and the quality of resources provided, i.e. habitat structure, plant species diversity, and the abundance and diversity of floral units.

Using a range of complementary methods (e.g. sweep netting and direct searches), natural enemies including ladybirds, hoverfly & lacewing larvae, spiders, predatory mite, and earwigs will be recorded in the hop canopies and from the alleyways.

Key hop pests will be recorded using direct searches and sticky traps. Key pests include damson-hop aphid (Phorodon humuli) and two-spotted spider mite (Tetranychus urticae), but all potential pests will be monitored.

To investigate levels of pest regulation service provided by natural enemies according to alleyway treatment, cards baited with aphids will be deployed to coincide with the arrival of damson-hop aphids. Depletion of aphids from the cards will provide an indication of the role of wildflower strips to support natural enemies of a financially important hop pest.

To investigate the benefits of implementing wildflower strips in hop yards for wider biodiversity gains i.e. species not directly linked with hop production, bee and butterfly transects will be conducted in the control (conventionally managed) and wildflower alleyways.

To investigate the influence of wildflower interventions on soil health and their contribution to net zero farming, soil samples will be collected. Soil analyses will include measures of soil organic matter, pH, and nutrient concentrations.

References

Albrecht, M., D. Kleijn, et al. (2020). The effectiveness of flower strips and hedgerows on pest control, pollination services and crop yield: a quantitative synthesis. Ecology Letters 23(10): 1488-1498.

Aguilar-Fenollosa, E., M. V. Ibanez-Gual, et al. (2011). Effect of ground-cover management on spider mites and their phytoseiid natural enemies in clementine mandarin orchards (I): Bottom-up regulation mechanisms. Biological Control 59(2): 158-170.

Canali, S., E. Di Bartolomeo, et al. (2009). Effect of different management strategies on soil quality of citrus orchards in Southern Italy. Soil Use and Management 25(1): 34-42.

De Deyn, G. B., R. S. Shiel, et al. (2011). Additional carbon sequestration benefits of grassland diversity restoration. Journal of Applied Ecology 48(3): 600-608.

Gillison, A. N., G. P. Asner, et al. (2016). Biodiversity and agriculture in dynamic landscapes: Integrating ground and remotely-sensed baseline surveys. Journal of Environmental Management 177: 9-19.

Hicks, D. M., P. Ouvrard, et al. (2016). Food for pollinators: quantifying the nectar and pollen resources of urban flower meadows. PloS one 11(6).

Lepsch, H. C., P. H. Brown, et al. (2019). Impact of organic matter amendments on soil and tree water status in a California orchard. Agricultural Water Management 222: 204-212.

Mann, C., D. Lynch, et al. (2019). Relationships between field management, soil health, and microbial community composition. Applied Soil Ecology 144: 12-21.

Mateos-Fierro, Z., M. T. Fountain, et al. (2021). Active management of wildflower strips in commercial sweet cherry orchards enhances natural enemies and pest regulation services. Agriculture Ecosystems & Environment 317.

Mateos-Fierro, Z., M. P. D. Garratt, et al. (2023). The potential of wildflower strips to enhance pollination services in sweet cherry orchards grown under polytunnels. Journal of Applied Ecology 60(6): 1044-1055.

Sharifi, M., J. Reekie, et al. (2016). Effect of cover crops on yield and leaf nutrient concentrations in an organic honeycrisp apple (Malus domestica 'Honeycrisp') orchard in Nova Scotia, Canada. Hortscience 51(11): 1378-1383.

Wolfe, D. W., A. T. DeGaetano, et al. (2018). Unique challenges and opportunities for northeastern US crop production in a changing climate. Climatic Change 146(1-2): 231-245.

Yang, Z. C., H. Li, et al. (2015). Effects on soil organic carbon and microbial biomass carbon of different tillage. AASRI International Conference on Circuits and Systems (CAS), Paris, France.          

Zízala, D., A. Juricová, et al. (2021). The potential risk of combined effects of water and tillage erosion on the agricultural landscape in Czechia. Journal of Maps 17(2): 428-438.

Details of the studentship

The studentship is offered for a four-year period on a full-time basis starting in January 2025. The studentship is campus based in Cirencester, but will involve travel to the University of Warwick, and extensive travel to field sites in Gloucestershire, Herefordshire, and Worcestershire. During the period of your studentship, you will receive the following:

• A tax-free annual stipend of £19,237 for three years.
• A fee-waiver for 4 years for UK home students* (expectation that full-time students complete in three years. If you enter year 4, the bursary stops but fees are waived).
• A budget to support your direct project costs, including dissemination costs.

*International students are welcome to apply but the difference in home and international fees currently at £5,500 and £18,050 per year respectively, would have to be paid each year by the student.

As a PhD student, you will be expected to play an active role in the life of the Royal Agricultural University. You will also be given opportunities to gain experience in learning and teaching under the guidance of your Supervisory team.

Supervisory team

Primary Supervisor:

Professor Duncan Westbury, Royal Agricultural University

Co-Supervisors: 

Dr Kelly Hemmings, Royal Agricultural University, 

Professor John Clarkson, University of Warwick

Application process

To apply please complete the application form below:

Application form for RAU PhD Studentship

It is expected that applicants will have the following qualifications / experience. In your application it is important to indicate how you meet these expectations:

• A Masters degree in a relevant discipline e.g. ecology, entomology, soil science, environmental science, biodiversity & conservation, or equivalent professional experience.
• A First or Upper Second (2.1) Honours Degree.
• Ability to contribute to the research design of the project.
• Experience of relevant research methods and skills.
• Experience of identifying invertebrates using identification keys.
• Experience of soil sampling and lab analysis.

It is also expected that applicants will be able to demonstrate the following:

• Ability to identify common grassland plant species.
• A sound understanding of and interest in both the project and the wider subject area.
• Proficiency in oral and written English.
• Computer literacy.
• Ability to organise and meet deadlines.
• Good interpersonal skills.
• Ability to work independently and as part of a team.

The interview

In person interviews will be held on 21 November 2024. Shortlisted candidates will be given at least seven days’ notice. In advance of the interview, shortlisted candidates will be asked to submit a sample of their written work (e.g. a publication or a dissertation). Alongside the interview, shortlisted candidates will be asked to give a 15-minute presentation on a piece of research they have previously undertaken (10 mins) and their ideas for the PhD (five minutes). The formal interview will last approximately 40 minutes. In addition to the formal interview, shortlisted candidates will be tested on their ability to identify a range of UK invertebrates with a focus on natural enemies of crop pests and pollinators; they will also be tested on their ability to identify some common British wildflower plant species.

For further information or an informal discussion on this project, please contact Professor Duncan Westbury (Primary Supervisor) via email (duncan.westbury@rau.ac.uk).