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Four farmers are investigating whether creating a bespoke herbal ley mix can help reduce flooding in their catchment. They want to test whether water infiltration and storage capacity can be improved in their soil by incorporating a higher percentage of deeper rooting species into the seed mix.
The Wyre Rivers Trust will coordinate the project and the Field Lab will compliment Brock and Calder Landscape Recovery (BCLR) led by Wyre Rivers Trust and its partners.
It is hoped that farmers will also see other benefits from the bespoke mixes, including improvements to their productivity through better drought resilience, potentially extending the grazing season and offering opportunities for them to partake natural flood management schemes.
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Most Natural Flood Management schemes tend to focus on field margins and water courses, for example, encouraging riparian tree planting and creating bunds or scrapes. There is limited focus on field scale management such as manipulating herbal ley species composition for reducing flooding, probably because there is very limited research on the topic.
However some evidence suggests that manipulating species composition to include a greater proportion of deeper rooting species can alter and increase soil-hydrological functions, thereby allowing more water to infiltrate the soil and increase water storage capacity.
Three herbal ley treatments will be tested on each farm:
Soil hydrological monitoring will be carried out monthly at each site throughout the two year project. A more comprehensive assessment of soil biological, physical and chemical properties will be taken annually during the growing season.
Data will be analysed to see which soil properties and soil-hydrological functions are significantly affected by the herbal ley treatments. In addition, the annual in-depth analysis will be used to generate a value for soil health using WRT’s soil health model, which gives farmers greater insight in to how their soil performs for a variety of agricultural and environmental outcomes.
On the two farms where the herbal leys were established in the autumn (the other two farms will drill in spring 2025) one herbal ley is doing better than the other. This is likely to be down to stock management, potentially the length of the grazing rotation or livestock type (one is grazing with cows and the other sheep).
This highlights the fact that good establishment methods are not enough to create a good herbal ley - but post establishment management is key. More information can on herbal leys establishment can be found in this article on Herbal ley establishment and management | Soil Association
This management aspect of the trial will be considered more in the final report.
Two seed mixes were to be used in the trial, a 'standard' herbal ley mix and an 'enhanced ley mix' which was a bespoke seed mix designed by Watsons seeds using data from the baseline soil assessments. The bespoke mix contained more deeper rooting legumes.
The fields were limed which had not been in the original plan, but which should benefit the legumes in the new leys.
Poor weather in the autumn unfortunately delayed the establishment of the herbal leys, and in the end only two farms were able to get the herbal leys in. The other two will drill in spring 2025. This introduces a new aspect to the trial: comparing autumn with spring established herbal leys. There will be enough replication of data collection points to allow for statistical analysis even though there will be more variables.
Pre-establishment the fields were grazed down and power harrowed, and the herbal ley seed mix direct drilled into the sward.
For more information see our article on Herbal leys advice
In late spring / summer 2024 baseline surveys were carried out on the trial fields.
March 2024
April 2024 - This was delayed to the summer due to wet and boggy conditions
April 2024 - April 2026
June 2024
January 2025
June 2025
July 2025
May 2026
Wyre Rivers Trust
NW Lancashire
Heather is a soil and ecosystems ecologist, who has a PhD in Environmental Science from Lancaster University. Her time in research was spent assessing the impact of climate, land management and biodiversity on grassland carbon and nutrient cycling. She is passionate about increasing understanding of the role soils can play in sustainable catchment management.
