Why Herbal Leys Deserve a Place in Your Rotation

Herbal leys are more than just a latest fashion in livestock grazing swards - they play a strategic role in arable rotations, delivering agronomic, environmental, economic and animal health benefits.

What are herbal leys and why use them?

Herbal leys are sown pastures, designed for rotational grazing and/or cutting, containing a diverse blend of plant species such as:

• Grasses (festulolium, cocksfoot, meadow fescue, timothy) - providing main biomass and yield,

• Legumes (red and while clovers, sainfoin, lucerne, birdsfoot trefoil) - fixing nitrogen and providing high protein, and

• Deep-rooted herbs (chicory, Boston plantain, burnet, yarrow) - improving overall nutritional value and resilience.

Our proven herbal ley seed mix includes intermediate perennial ryegrass, cocksfoot, festulolium, meadow fescue, timothy, Boston plantain, crimson clover, lucerne, red clover, sainfoin, sheeps burnet, sheeps parsley and yarrow to help optimise establishment, palatability, yield and resilience.

When growing in the right situation and managed well, they:

Provide forage in unreliable weather

• Longer grazing window - different species peak at different times, smoothing out feed supply across the season and extending the season into late spring, summer and autumn. Livestock also tend to graze diverse swards more evenly than monocultures, which usually means they can be grazed for longer.

• Handling wet weather and droughts - rooting depth and complementarity help increase resilience and access moisture and nutrients from lower in the soil profile, keeping pastures productive through droughts (Grange, G., 2021) and recovering faster after waterlogging.

• Consistent yield - farmers report more stable production across variable seasons, an asset in increasingly unpredictable UK weather.

Improve livestock health and performance

• Higher nutritional quality - diverse leys contain more minerals and trace elements than grass-clover swards, and can have increased crude protein content, helping prevent production-limiting deficiencies. A recent study found that forbs were highest in Iodine (I) and Selenium (Se), and legumes were richer in Copper (Cu), Cobalt (Co), Zinc (Zn) and Iron (Fe) (Darch, T., et al, 2020), although selecting species most suitable for the soil type is key to unlocking these benefits.

• Natural parasite control - anthelmintic properties of certain plants (e.g. sainfoin, chicory and birdsfoot trefoil) may help to reduce wormer use and improve performance, especially in lambs and calves. In one recent study, faecal egg count scores were reduced by 78% in herbal ley grazed lambs in spring (Cooledge, E., et al, 2024). Other than condensed tannin concentration, herbal leys may also be helping to interrupt the parasites' lifecycle through taller sward height at time of grazing limiting larvae's ability to climb high up enough to be ingested (Jordon, M., et al, 2022.)

• Optimised livestock growth or finishing rates - rotationally grazed herbal leys can deliver as good as or better liveweight gains than ryegrass-dominated grass-clover leys

• Lower bloat risk - including condensed tannin-rich species helps offset the bloat potential of high-legume swards (Lüscher, A., et al, 2014.) Although it's also important to provide free access to rock salt and introduce stock to the ley gradually.

Deliver long-term soil and environmental benefits

• Nitrogen fixation - legumes in the mix can fix 180 kg N/ha (source: RB209), reducing bagged fertiliser costs and emissions.

• Building soil structure and organic carbon - complementary deep and fibrous roots help create drainage channels and build soil aggregates, ease compaction, and improve water retention and infiltration. They also help build soil organic carbon through root exudation, promoting metabolic activity of soil microbiology.

• Managing weeds - mixed farming offers key opportunities for weed management, particularly of those with increasing herbicide resistance, such as blackgrass. Research also suggests that diverse swards better supress weeds compared to monocultures, although weed control options are limited in a diverse mix.

• Boosting biodiversity and reducing emissions - flowering herbs attract pollinators, beneficial insects, birds and increase earthworm activity, supporting the wider farm ecosystem. Secondary metabolites such as condensed tannins in certain species can also help reduce methane and nitrous oxide emissions associated with livestock production (Mueller-Harvey, I., et al, 2019.) Research is ongoing to fully understand how these metabolites can enhance production and help deliver longer-term ecosystem service benefits.

Add up economically

• Lower inputs, better margins - greater dry matter production with less nitrogen, better productivity, reduced mineral and concentrate use and extended grazing all contribute to improved gross margins.

• Government support - SFI payments (CSAM3 and SAM3) reward well-designed herbal leys, helping offset cost and improve ROI calculations.

Herbal leys can fix 180 kg N/ha, extend the grazing season, reduce parasite burdens and be useful for blackgrass control

Getting the best from herbal leys

While the potential benefits are many and varied, managing the more challenging aspects of establishment and maintenance of herbal leys, as well as careful species selection, are key to delivering these.

Herbal ley establishment: step-by-step

• Establishment success depends on selecting a suitable seed mix. There is little benefit in drilling a high-quality mix without carefully considering soil type, local climate, pest (e.g. leatherjackets) and weed (e.g. docks, thistles and chickweed) profile and abundance and herbicide use in the previous crop(s). Our team can help you mitigate the risk of unnecessary reseeding, with expert advice and tailored species mixes where required.

Species such as sainfoin, cocksfoot and yarrow are more suited to lighter, sandy and free draining soils, while Timothy, meadow fescue and burnet prefer heavier clay.

• Variety selection is not to be overlooked. For example, Boston plantain has been shown to be much higher yielding than the more popularly used varieties in the UK. This is largely because it is much later to flower, meaning that it remains leafier for 25-28 days longer producing excellent forage even when drought causes stress in other species. Productivity is still a key driver of economic output.

• When overseeding an existing pasture, your mix should have fewer grasses to give legumes and herbs a better chance of establishing. Higher seed rates, seedbed preparation (including dealing with any thatch and spraying, grazing or mowing established grass to 4-5 cm up to germination) and choice of machinery are key for competition control.

Herbal ley grazing: pasture management and species composition

• First grazing needs to be timed carefully to ensure that roots are sufficiently established and avoid poaching, which in turn will support persistence of the various components of the ley. For example, look for 6-8 fully developed leaves on the plantain and chicory in a newly established sward, and use the "pull test" on grasses to check that they snap instead of uprooting.

• Retention of sown components of a herbal ley mix to maintain diversity and productivity is often cited as a key challenge (Jordon, M., et al, 2022). Although species composition will change over time, optimising persistence requires careful pasture management e.g. rotational grazing, or even mob grazing, to allow recovery time (28-40 days), and nutrient monitoring. Certain species are more persistent under grazing (e.g. Boston plantain), although herbs and legumes are generally sensitive to continuous grazing and need sufficient rest periods.

• Grazing taller herbage than is customary with ryegrass-clover mixes is beneficial, while overgrazing must be avoided as most herbs and legumes grow from a crown just above ground.

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📞 Call us on 01480 890686 or email info@oakbankgc.co.uk to discuss a herbal ley strategy that works for you

🐑 View our multi-species herbal ley seed mixture here →

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