Grassland re-seeding: how to establish multi-species swards

Guylain Grange from Johnstown Castle research centre gives information and advice on establishing multi-species swards

As days are warming up and the ground is drying, the time is here for reseeding some paddocks. There is a lot of interest in multi-species mixtures at the moment, and here we give advice for those wanting to sow them.

Multi-species mixtures are a combination of diverse forage species with specific characteristics. You will know about perennial ryegrass – white clover mix, but the opportunities are much larger with other types of clover or herbs such as plantain or chicory.

The advantages of multi-species swards are to maintain a steady growth rate at reduced fertiliser application. A well-managed clover content in the sward (20-50%) can allow you to cut mineral fertiliser application by more than half in summer, at a time when it is critical for greenhouse gases emissions. Plantain and chicory also act at different levels to avoid losses of nitrogen (N) on the farm: reduced leaching, better N use by animals, and less emissions from urine patches.

At Teagasc, Johnstown Castle, multi-species swards with ryegrass, red and white clovers, chicory and plantain fertilized with 150 kg of N yielded more than perennial ryegrass receiving 250 kg of N under a regular cutting regime. Moreover, in 2018 these mixtures had better resistance to drought than ryegrass. A grazed trial is currently on-going at Johnstown Castle dairy farm.

What you should know if you choose multi-species

Different species means different behaviours, so you must choose your mixture depending on your objectives. Here is a summary of what you can look for:

First grazing of the year on multi-species mixtures established last summer. In spring, sward is dominated by perennial ryegrass and plantain. Active growth of clover and chicory starts when ground temperature is over 8°C.

You can establish a multi-species grassland in the same way as any grassland. To calculate seeding rates, decide your target proportion and apply them to monoculture rates. You can then add 10% as there is competition at establishment. Here is an example for a spring milk grazing system, similar to what we are using at Johnstown Castle:

This kind of seed mix (or something similar) can be purchased at your regular supplier if they don’t already have advised mixtures.

In an established ryegrass sward, you can also try over-seeding after a silage cut or a tight grazing, but chances of success are much lower.

Managing a multi-species sward

Because this mixture contains broadleaf species, do not apply any post-emergence herbicide! Research trials clearly show that multi-species mixtures are excellent at resisting weed pressure.

Fertiliser application should be strongly reduced in summer (May-September) and nitrogen from clovers should compensate for this.

By including herbs, you reduce the risk of bloating, but avoid moving animals straight from a grass-only pasture to a mixture with high clover content. Optimal grazing rotation and pre/post grazing covers are quite adaptable, and general advice would be to extend rotation to 25 days.

We are continuing to learn how to manage these swards, and will share our lessons over time.

 In summer, clover and chicory take the lead, compensating for lower growth rates of perennial ryegrass (Balanced mixture of grass, clover and herb under cutting regime - July 2018).