New tool identifies plant species in herbal leys

3 May 2023

Farm Carbon Toolkit’s Hannah Jones describes a new tool designed to help identify which species are right for an individual farm.

The complementary nature of the benefits seen from multi- species (or herbal leys) are well documented. Introducing more species of grasses, legumes and herbs into your grassland benefits soil health and the resilience of forage production.

Research on multi-species is growing, building a scientific base to their successful use. To date, findings show diverse swards had higher dry matter yields and digestibility, produced more milk and were better at suppressing weeds. Ref: TOMS (

Other potential benefits include:

  • Nitrogen fixation by legumes resulting in less ammonium nitrate needed on cutting ground or none on grazing land
  • Drought resilience from deeper rooting species, such as plantain and red clover
  • Improved soil health through enhanced soil biology, structure and carbon sequestration
  • Reductions in leaching from greater root distribution and plants with different nutrient requirements through the growing season
  • Extended grazing season and a more consistent platform
  • Forage anthelmintics which complement prophylactic pharmaceutical treatments
  • Improved resources for pollinators

One size does not fit all when it comes to sward composition though. Not all species suit all field conditions. The variation in establishment according to location, climate and topography can create uncertainty and reluctance, so it’s important to work out what’s best for your farm.

A common approach to building confidence with herbal leys is a stepwise introduction of species to your existing ryegrass reseed.

For cutting leys, the tall bulky legumes red and alsike clover provide good levels of crude protein. Red clover is more aggressive, but some varieties are short-lived. Alsike clover shows better tolerance of more acid conditions and can last longer but has a lower DM. On dry sandy soils, with pH above 6.5, try lucerne but make sure it is inoculated with the right Rhizobium root bacteria.

If soils are tight, plantain can be used in cutting leys, but it won’t contribute much to silage, and avoid chicory as it requires careful management. It grows woody in the mid to late season and can affect moisture distribution in the clamp, although can be useful in one early season cut.

For good silage, build the grassy canopy with a range of growth types. Increase bulk by adding festulolium to Italian and perennial ryegrasses although quite short-lived. Timothy can fill in the under canopy, but it has lower digestibility than ryegrasses.

In grazing leys, the height of grazing affects which species survive. If only grazed by cows, lucerne, red and alsike clover are tall with a high growing point, so can be useful. If sheep are involved, white clover and birdsfoot trefoil are more suitable dominant legumes. Birdsfoot trefoil is a useful high tannin species with the potential to provide health benefits to livestock and is non-bloating.

Herbs for grazing leys include plantain, chicory and yarrow as a baseline. Burnet can be added on stony, free-draining land but it doesn’t thrive in other conditions. For grazing grasses, use a range of ryegrasses with different heading dates, plus timothy and meadow fescue. Cocksfoot thrives where many grasses fail, but its habit of becoming ‘tussocky’ with a drop in digestibility can put farmers off if their land supports more digestible grasses.

The characteristics and relative benefits of each species can be found on the TOMS website under TOMS App and Cards.

To trial a herbal ley, pick one of your lower yielding fields. Diverse swards can provide resilience to conditions in which ryegrass swards suffer buffering the variation of waterlogging, stony caps and thin soils. But always deal with weeds first as there are few control options after sowing.

Two common approaches to introducing more species are ‘casting the net wide’ by sowing a diverse mixture to see what grows or introducing one or two species to an existing grassland mix. The first is more expensive but gives you a quicker answer. The second is slower, more sequential and less risky but you may not optimise your grassland mix.

With both, you need to know which species are growing and how diversity changes over time. A new app from Duchy College’s TOMS Agritech Cornwall project helps do just that, with a free option to log locations across a field. Like the traditional soil sampling ‘W’, this helps you understand which species dominate at different times of the season and under specific conditions on your farm.

Currently only available on Android, details can be found on the TOMS website or by visiting the Play Store, searching for ‘sward app’ (blue chicory icon).

The Agritech Cornwall and the Isles of Scilly project supported business research and development for agriculture (agri-tech) across Cornwall and the Isles of Scilly. It was part funded by the European Regional Development Fund Cornwall Council and the Council of the Isles of Scilly.