DLF Multi-Species Agronomy Guide
What is a Multi-Species Sward?
A multi-species sward is a mixture of three or more species whose growth characteristics complement each other resulting in improved productivity compared to when each species is grown on their own.
Typically the species used, come from three plant groups, i.e., grasses, legumes, and herbs, with each species bringing different benefits to the sward.
What Multi-Species Mixture Should I Sow?
When deciding on a mixture, soil type and local climate are important as some species are better suited than others to particularly wet or dry conditions.
Species suitable for wetter soils include timothy, birdsfoot trefoil and burnet, while species like cocksfoot, lucerne and chicory will thrive in light, dry soils.
Depending on your soil-type a mixture of the specialist species above and some all-rounders like perennial ryegrass, white clover and ribwort plantain would make for a very productive sward.
More species in a mixture means a more resilient sward to extreme weather events like drought.
DLF’s 6-Species Herbal Ley contains perennial ryegrass, timothy, red and white clover, ribwort plantain and chicory. This mixture will provide a good balance of productivity and diversity across a range of soil types.
A more diverse sward can provide a range of additional benefits including forage quality, weather resilience and biodiversity. Sinclair McGill CastleHerb mixture contains 15 species: 5 grasses, 5 legumes and 5 herbs for maximum diversity effects.
When should I sow a Multi-Species Sward?
Multi-species swards should be sown into a warm (~10°C), moist seedbed between April - September for optimal establishment.
Sowing your Multi-Species Sward - Reseeding
A conventional reseed will give the best results in establishing your new multi-species sward, but the following points should be remembered when sowing:
- Ensure soil fertility (pH, P and K) is adequate as per recommendations for grass swards.
- Address any weed issues with herbicide before sowing as a herbicide cannot be applied to a multi-species sward. This is crucial.
The similarity in the growth habit of herbs like plantain and chicory to common grassland weeds like docks, means that once these species get established, there is no space in the sward for docks and other broadleaf weeds. Small outbreaks of weeds can be spot-sprayed if necessary.
- Cultivate to form a fine, firm seedbed.
- Apply lime as required.
- Roll the seedbed before sowing to ensure it is firm.
- Seed can be direct drilled no more than 1cm deep or broadcast.
- Sow seed at a rate of 27-32kg/ha or 13-15kg/ac.
- Roll again! A firm seedbed and soil contact is vital for the small seeds of legumes and herbs.
- Allow 8 weeks before the first grazing to let herbs establish strong taproots.
Overseeding a Multi-Species Sward
Clover and herbs can also be oversown into existing grass swards to achieve the benefits of a multi-species sward. These should each be oversown at a rate of 1.5-2kg/ha. Remember, we want to allow light penetrate down to the ground for the new seedlings and reduce competition from the existing sward.
- Oversow after a silage cut or tight grazing.
- Graze lightly.
Nitrogen Fertiliser for Multi-Species Swards
One of the biggest attractions of multi-species swards is their potential to reduce the requirement for nitrogen fertiliser.
Many studies have reported multi-species swards receiving little or no nitrogen achieving similar yields to grass swards receiving ~300kg N/ha per year.
Achieving such an outcome on-farm will depend on maintaining a decent proportion (20-30%) of legumes in the sward. Regular grazing will help to encourage and maintain clover in the sward.
Large nitrogen applications will have a negative effect on legume persistence; however, a small amount in spring can be useful to feed grass and herb species before legumes begin nitrogen fixation in summer. In this case, up to 50kg, N/ha early in the growing season should not have a significant adverse effect on legume persistence. Alternatively, slurry can be applied during the early part of the year.
Grazing Your Multi-Species Sward
Multi-species swards can produce high yields of quality forage when managed correctly with potential for excellent animal performance.
The management guidelines for grazing multi-species swards are similar to grass swards with quality directly related to the proportion of leaf and stem. However, there are a couple of important points to remember when grazing multi-species swards.
- Rotational grazing will lead to better sward quality, utilisation, and persistence than continuous set stocking.
- Providing animals access to paddocks for a short time (1 – 3 days) will help maintain sward diversity by preventing the selective- and over-grazing of more palatable herb species.
- Keep post-grazing sward heights to between 4 and 6 cm so not to damage the growing points of legumes and herbs.
- It is important to provide a sufficient rest period for multi-species swards to recover from grazing.
- At peak production in mid-season multi-species swards can keep up with a 21-day rotation. However, it is advised to extend the rest period in the shoulders of the year to aid persistence.
The greatest benefits of multi-species swards compared to grass swards occur in summer when grass swards are less productive.
For sheep and beef systems, the above management points can be adapted as follows:
- Where paddocks are not available, large fields can be divided into smaller blocks with temporary fencing.
- It is important to limit the time spent grazing each section to 1-3 days to prevent over-grazing.
- Swards can be grazed at pre-grazing heights ~10 inches (25cm) down to ~2 inches (5cm).
A Note on Persistence of Multi-Species Swards
It must be noted that herbs like ribwort plantain and chicory will likely never be as persistent as perennial ryegrass. The productive lifespan of these herbs in a mixture is between 3-5 years. This should not be a barrier to the use of multi-species swards, however.
The savings in nitrogen fertiliser alone should far outweigh the cost of oversowing herbs every 4 or 5 years. In addition, the benefits to animal and soil health and the wider environment are significant. At worst, you will be left with a grass-clover sward and a much lower fertiliser bill!
In light of a changing climate and changing policies, we must adapt how we farm, and multi-species swards have a considerable role to play.
Multi-Species Swards for Silage Production
Multi-species swards are often thought as better suited to grazing than silage production. While this may be the case, excellent quality silage high in protein and minerals can be produced from a multi-species sward.
The following tips will help to ensile your multi-species sward successfully:
- Cut the crop to a stubble height of 6-8cm.
- Multi-species swards typically have a lower DM content than grass swards due to the presence of legumes and herbs. Therefore, the crop must be cut in dry conditions.
- Allow the crop to wilt for 24 to 48 hours in dry conditions.
- Aim for a DM concentration of 25-35%
- Care must be taken when mowing and handling the crop to reduce leaf shatter.
- Avoid using a conditioner mower.
- Avoid overwilting and excessive handling.Silage additive application may also improve preservation.
*Multi-species Swards produce more quality forage than grass swards during the summer months due to the inclusion of legumes and herbs.
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