Tackling Water Pollution from Agriculture
Lessons from Welsh Water's Weed Wiper Trial
1. What was the weed wiper Trial?
Diffuse pollution from agriculture is one of today’s major environmental problems, with impacts for water quality, cost of water treatment and reduced recreational potential of water resources.
In 2013 Welsh Water detected increased concentrations of the herbicide MCPA (2-methyl-4-chlorophenoxyacetic acid - a chemical that is extensively used in agriculture to control broad-leaf weeds such as thistles, docks, and the common rush) in watercourses across Wales. Although these levels were too low to pose a risk to those drinking the water, they were of a concern as if they continued to increase they would breach rigorous drinking water standards. By safeguarding and improving raw water quality before it gets to water treatment works Welsh Water can avoid the need for using additional chemicals and energy. This helps keep bills low for customers and protects the environment.
Welsh Water’s discussions with stakeholders revealed that it was common practice for farmers to boom spray MCPA to tackle common rush infestation, which is mainly a problem in permanent pastures on poorly drained soils in high rainfall areas, especially after wet winters and/or summers.
To address this issue, Welsh Water decided to work with farmers and other stakeholders in the land management sector, placing particular emphasis on providing farmers with advice and increasing their awareness of pesticide loss to water courses. In 2015, Welsh Water launched the weed wiper trial in two targeted catchments: the Rivers Teifi, and Wye, and expanded it to a third catchment, River Towy in 2017 (see Figure 1). The initiative offered farmers in these catchments free hire of a weed wiper and disseminated best practice guidance (Box 1).
Box 1: Overview of the weed wiper trial
The weed wiper trial is a voluntary approach to stimulate adoption of best land management practices, with the specific intent to reduce pesticide loss from terrestrial to aquatic ecosystems and thus improvement in water quality.
Between 2015 and 2019, there was 292 weed wiper hires across the targeted catchments. A weed wiper is a technology where a wick or brush is wetted with herbicide mounted on a boom or frame and dragged or rolled across the tops of the taller weeds. This technology allows treatment of taller weeds by direct contact, without affecting desirable shorter plants in the grassland sward beneath. The technology has the benefit of avoiding spray drift that occurs with other conventional methods of application that use tractor mounted or self-propelled sprayers equipped with long booms. Only glyphosate-based products are licenced to be used in the weed wiper.
Welsh Water expected that by offering farmers first-hand experience of the weed wiper technology it would help them appreciate its benefits. It was hoped that by ‘trying before buying’, farmers would be more likely to adopt the weed wiper to provide longer-term control of weeds. The best practice advice disseminated through the scheme was aimed at raising awareness of adopting an integrated approach to weed control to reduce reliance on pesticides.
2. What did we do?
Researchers at the University of Leeds and Scotland’s Rural College (SRUC) in partnership with Welsh Water carried out research to understand whether and how the weed wiper trial had improved farmers’ awareness and triggered changes in the way they carried out farming practices; and whether ultimately this had contributed to reducing pesticide water pollution.
The research involved two main aspects:
1. Analysis of raw water quality data from Welsh Water’s water treatment works from 2006 to 2019 in the three targeted catchments where the weed wiper had been trialled (Towy, Teifi and Wye); and from three control catchments of similar characteristics but where the weed wiper trial had not been promoted (Cleddau, Teme and Usk). (Figure 1)
2. In-depth interviews with farmers and other relevant regional stakeholders. A total of 22 interviews were conducted between July 2019 and February 2020. The interviews were aimed at understanding whether and how awareness had contributed to adoption of best practices for pesticide use and to the improvement of water quality.
Figure 1: Location of the six study catchments.
Box 2. Examples of statements from some farmers.
The information pack was good and helped me…without this trial I wouldn’t have tried out the [weed wiper] machine for myself and I’d probably still be using a knapsack.”
…knowing what to do. We know there are issues of water supply so we're very conscious of where our water supply is on the farm and where our neighbouring water supply is, so we're not spraying near them as well. And then we'll watch the wind speed so there's no spray going into the watercourse as well.”
The ability to try out one of the weed wipers for free before committing to buying one was the best way of me improving my knowledge and understanding of pesticide management. Without hiring one for free I would probably still be using a boom sprayer…The machine worked well for me, that’s why I went to buy my own. I now only use a weed wiper.”
I now only use a weed wiper and several of my neighbours have also bought their own weed wiper using grants.”
3. Was weed wiper trial successful in achieving its goal?
Our analysis suggests that the trial was successful because of the following:
- MCPA concentrations declined significantly in the catchments where the weed wiper trial had been carried out (mean decrease = 45.2%) compared to in the control catchments (mean decrease = 10.9%).
- All catchments where the weed wiper trial had been carried out observed a significant decline in MCPA detections (with the highest decline observed in the Teifi), while only one of the control catchments (the Teme) recorded a decline in MCPA.
- The observed water quality improvements were associated with farmers’ improved understanding of the link between weed management and water quality in streams, and their adoption of best management practices.
- The trial increased farmers awareness pertaining to pesticide management, weed wiper use and other lower risk weed management practices (Box 2, Statements 1 and 2).
- The trial provided farmers the opportunity to hire weed wipers for free and this has contributed to farmers changing the way they used pesticides (Box 2, Statements 3 and 4).
4. What might hinder adoption of the weed wiper technology?
The trial was successful, but the research also highlighted that there are a number of factors that may prevent some farmers from using the weed wiper outside of the trial (where it was free to hire):
- Unwilling to move away from current practices: some farmers are less likely to change practices because they feel uncomfortable about dealing with a new technology and prefer to keep practices they are used to and know work.
- Lack of access to resources: some farmers indicated that not having any of the required resources (such as the weed wiper, and quad bike) is a major barrier to using the weed wiper. This is linked to financial constraints and regulations.
- Topography of the landscape appeared to influence practices as some farmers mentioned that very steep land makes it difficult to move spraying machines.
5. How can key stakeholders support adoption of best practices?
The research also provided Welsh Water with evidence about how to improve engagement with land management to encourage the adoption of best management practices (beyond pesticide use). They included the following:
- Provide tailored evidence to farmers.
- Use non-technical language to explain the problem and solutions to farmers.
- Support training on best management practices for farmers.
- Carry out farm visits to understand the situation on the ground and to provide tailored advice.
- Increase funds, grants, and incentives for adoption of the weed wiper for pesticide application.
- Scale up the weed wiper trial to other catchments.
- Vital to build relationship with farmers in order to build trust and support for the programme.
- Work collaboratively with local stakeholders trusted by farmers.
Acknowledgements
This work was carried out by Murat Okumah, Julia Martin-Ortega, Pippa Chapman, and Marie Ferré from the University of Leeds, and Paula Novo from Scotland's Rural College, in partnership with Sarah Jones, Phillippa Pearson and Tara Froggatt from Welsh Water.
The research was funded by the University of Leeds International Doctoral Scholarship (2017-2020). Many thanks to water@leeds and Sustainability Research Institute (Economics and Policy Research Group) for providing funds to support the fieldwork for this research. We are grateful to the farmers and stakeholders who participated in this research. This research has been published in a peer reviewed scientific publication:
Please cite this document as:
Okumah, M., Chapman, P.J., Martin-Ortega, J., Novo, P., Ferré, M., Jones, S., Pearson, P., Froggatt, T. (2021). Tackling water pollution from agriculture: Lessons from Welsh Water’s Weed Wiper trial. University of Leeds-SRUC brief.
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