What are you looking for?


Herbal leys for dairy

Supported by:


This group of ten dairy farmers is investigating consistency of forage quality in diverse ley species.  The diets on these farms are highly dependent on forage with low level concentrates being fed. Therefore, maximising the value of the sward is very important.

The farmers involved have been impressed with the performance of their herbal leys in relation to forage quantity, drying out wet fields, improving soil structure and showing positive signs regarding soil health and fertility.

The group want to expand on this performance by finding species mixes that produce the most consistent performance for their soils as well as optimising nutritional feed value. They also want to better understand the benefits and how to grow them to the best potential.

How it works

A herbal ley is a complex seed mixture of grasses, legumes and herbs, sometimes up to 17 species.  This mix brings a range of benefits to forage, livestock health and soil fertility. 

The deep rooting species in the mixture add drought tolerance when grown on thin soils or during dry summers, remaining green and palatable for much longer than other forage mixtures.  They also mine the soil for important nutrients and minerals, making them available to the grazing livestock and lowering the need for bought in concentrates. 

The high legume content fixes plenty of nitrogen and increases the protein content.

The mixture of species also ensures a longer growing season and certain species are said to have anthelmintic properties, which helps to reduce worm burden in livestock, creating less reliance on artificial wormers.

Trial design

Each farmer will select 3 locations on their farm: a newly sown sward, a 1-2 year old sward, and an older sward (3/4+ years).

When the grazing cycle moves around the farm and hits one of the identified locations, the paddock or grazing strip will be divided in two. The cows will be left to graze one part of the area to leave the sward at what the farmer would personally consider an “optimal” residual.

On the other half of the sward the cows will be removed early, so that the residual remaining is greater that the considered “optimal” height.

Optimal height and greater residual height will be measured using a plate meter.

Latest updates

Most of the triallists have not been able to sow their leys yet, however those that are using existing leys or have managed to sow and get some growth are hoping to take measurements. The group coordinator is sending out measuring equipment for the farmers to do this.


This methodology is still under progress.

Grazing frequency and management through the season will be investigated in order to:

1. Optimise sward regrowth after grazing and

2. Optimise longevity of species diversity in order to maintain a harmonious balance of species throughout the season (over 4+ years)

Both of these elements should then optimise the nutritional value of the sward throughout the season and analysis of this will be competed.

Additionally the trial will provide an opportunity for the farmers involved to gain additional skills in species identification in their fields. They will also be able to compare the effects of management and varying seed mixes on different farms with varying soil types and climate.


 The agreed methods aim to look at grazing frequency on:

1. Established mixes, considering the impact primarily on species composition, dry matter availability and feed quality.

2. The impact of grazing frequency on newly established herbal leys – where a bespoke mix is selected for that specific farm.

On each farm farmers will select 3 locations, were possible one site will be in a newly sown sward, one is a sward 1-2 years old and then a third in an older sward (3/4+ years).

On some farms there will be perhaps only one site to monitor in the first year as the herbal ley sown this spring will be the first diverse sward on the farm. Other farms will not have new leys sown this spring so will only be monitoring older swards in this first year.

When the grazing cycle moves around the farm and hits one of the identified locations. The paddock or grazing strip (if strip grazed) will be divided in two. The cows will be left to graze one part of the area to leave the sward at what the farmer would personally consider an “optimal” residual (A). The other half of the sward the cows will be removed early (this is yet to be defined – by measuring via days or height on the plate meter), so that the residual remaining is greater that the considered “optimal” height (B). Optimal height and greater residual height will be measured using a plate meter.

New herbal leys sown in spring

Bespoke mixes will be selected for the individual farms that are able to sow new herbal leys this spring. Ian Wilkinson will advise on appropriate mixes for each farm.

Data collection

Dates will be recorded when the cows enter and exit a trial location and from both parts of the grazing area the following records will be taken before the cows enter the site and then once exiting the site.

From three randomly thrown quadrats farmers will record species composition, based on % cover grasses, legumes and herbs. Additionally farmers will identify where possible presence of key indicator species such as Chicory, Ribgrass forage herb, Burnett, Yarrow, Trefoil and Clovers where possible. Photographs of the quadrat will be taken in order to help verify species composition where there are uncertainties.

The researcher will visit some of the farms at key points where possible to assess sward diversity. Due to the fast nature of the decisions that will be made by the farmers when moving the herd, it won't be possible for the researcher to carry out quadrat recordings before and after leaving the trial sites. The researcher may also undertake soil health/structure monitoring on visiting the farms.

The forage in the quadrat will be cut and weighed and then some of the samples will be sent for nutrient analysis (potentially including protein and fibre content and ME value) as well as dry matter content. Raw height measurements using a plate meter will also be taken by the farmers.

The group, including 8 of the farmers, coordinator Kate Still, herbal leys specialist Ian Wilkinson and researcher Anna Thomson, met to outline their priorities for the field lab aims and leading on from this their methods.

Many of the farmers are already growing herbal leys whilst others aren't, bringing a good range of experience to the group. Some have a few year old swards, whilst others have been growing them for several years. Most of the group will be planting new leys this spring of a bespoke mix for their farm, and/or focus grazing management on existing swards of varying ages.

As those that already grow herbal leys feel confident that they do improve soil health and have benefits to their livestock, the aim focused on determining the following:

a) What is the nutrient value of the herbal ley swards (at varying ages)

b) How can the herbal leys be best managed for optimal species diversity, longevity and forage production

Initial methods looked at giving different lengths of grazing time (one strip longer than another) to evaluate the effects on the sward. Additionally the effect on regrowth of the sward depending on the height of residual left. Farmers will likely take sward cuttings from quadrats to be sent off for nutrient and dry matter analysis, as well as recording the species present and weighing fresh weight of the forage. These measures will be taken before the cows go in and once removed.

Some farmers undertake mob grazing whilst others paddock graze, so these differing systems will need to take different approaches to the trial. Weather also influences the growth of the leys, and the farmers will therefore judge when the optimal height of the sward (instead of a fixed number of days grazing) and then have an option which leave a greater residual.

This methodology is still under progress and the next steps will be to solidify how each farmer undertakes the field

The group shared details of existing practices /experience with herbal leys. Most of the group have been growing some, ranging from a few fields to 2/3 of farm. Generally they are very impressed with their ability to produce lots of forage, dry out wet fields, improve soil structure, positive signs regarding heard health & fertility. The group want to understand them better and want to demonstrate this consistency and reliability to others while maintaining production.

The researcher introduced a new trial at Reading University which focuses on beef cattle, looking at 3 herbal leys of varying diversity compared to a rye grass control and monitoring cattle growth rates and nutrient utilisation.

Ian Wilkinson from Cotswold Seeds gave some background on herbal leys for dairy farms. He highlighted how dairy farmers need confidence in consistent quality forage but how herbal leys could lower cost of production (no fertiliser input required), extend the grazing season, are drought resistant, have medicinal benefits, better extraction of soil minerals as deep rooting, and can be included as part of Environmental Stewardship. However, they need to be managed well to maintain diversity, rotational grazing and mob grazing most effective with back fencing to allow regrowth to establish.

On a farm walk the group looked at a variety of herbal leys at varying ages and considered the diversity of species, ground cover, grass regrowth, soil health/structure. Additionally there were discussions on how to measure total dry matter with herbal leys, the flaws of plate metering, benefits of fixed rotation, length of grazing round, what seed mixes to use and the amount of grass in the mix.

There is interest in nutrient/medicinal benefits but most felt this isn't suitable for field trials. The initial impressions are that the success of the field lab will be predominantly measured in production. The group will be meeting again in the new year to solidify field lab aims.

Field lab starts and methods finalised

April 2018

Data collection

July 2018

First year review

September 2018

Sow second year of leys

April 2019

Data collection

July 2019

End of year results analysis

October 2019

Data collection

March 2020

Data collection

May 2020

Results analysis

October 2020

Group Coordinator

A portrait of Kate Still.
Kate Still

Soil Association

South West England

Specialist in animal welfare; dairy and sheep farming experience; former farm business consultant and advisor on agri-environment schemes and conservation; Animal Welfare Advisor on AssureWel, Soil Association. Kate is assisting in group co-ordination and additionally working on another project (RELACS) focusing on antibiotic reduction and udder health. This field lab with provide beneficial information to the farmers in the RELACS project.


A portrait of University of Reading.
University of Reading

University of Reading


Downloadable Reports

No downloads available.