Farm Ireland

Tuesday 12 December 2017

Opt for ryegrasses to aid grass growth

Perennial varieties 'will greatly increase profits'

Caitriona Murphy

Caitriona Murphy

Old, unproductive grass swards are costing Irish farmers €200-300/ha every year compared to reseeded pastures.

Speaking at a Germinal Seeds reseeding conference, Teagasc grassland expert Michael O'Donovan warned that farmers are also suffering further losses by not reseeding because of the improved response to nitrogen that reseeded paddocks show when compared to old swards.

Teagasc research has highlighted massive variations in grass production, both between farms and within farms.

There is a 40pc difference in grass production between the most productive grassland farms and the least productive units in the country.

However, there are also stark differences in grass production levels even within farms.

Analysis has shown that there can be as much as a 60pc difference between the amount of grass grown on one part of a farm to another part of the same holding.

While there are numerous reasons behind this difference, including poor soil fertility, soil type, drainage issues and poor management, the most obvious is the lack of perennial ryegrass within pastures.


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Mr O'Donovan highlighted the benefits of a grass sward where perennial ryegrasses are the dominant variety:

  • Grass swards with high levels of perennial ryegrass are more nutrient-efficient because they have a 24pc better response to nitrogen.
  • Perennial ryegrass-dominated swards have a higher dry matter production, especially in spring. High levels of perennial ryegrass reduce seasonality and ensure a more even grass growth curve across the season.
  • Perennial ryegrass-dominated swards have carrying capacity that is 0.8cows/ha higher than other swards and improve grass usage by 3t of dry matter.
  • The reseeding cost, estimated at €540/ha for this year, will be returned within two years of re-seeding with a perennial ryegrass-dominated mixture.

On the other hand, having a low level of perennial ryegrass in the swards has a major impact on profitability, warned Mr O'Donovan.

Compared to a high perennial ryegrass sward, one containing only 65pc perennial ryegrass will reduce profitability by €111/ha.

As the level of perennial ryegrass in the sward declines, the effect on profitability worsens. A sward with only 40pc perennial ryegrass will reduce profitability by €202/ha, while a sward with only 10pc perennial ryegrass will reduce profitability by a massive €292/ha.

Mr O'Donovan recommended that any sward with less than 65pc perennial ryegrass should be reseeded.

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