Farm Ireland

Wednesday 17 January 2018

Mixing it up in grass seed variety choices

Use Recommended List to decide which characteristics make up the best mixes for your soil types

Caitriona Murphy

Caitriona Murphy

Perennial ryegrass, Italian ryegrass and white clover account for practically all of the grass/clover seed sold in Ireland.

Of these, perennial ryegrass is by far the most important, accounting for around 95pc of forage grass seed sold here. Other species of grass and clover are not commonly used.

Individual varieties of grass differ in performance characteristics, depending on maturity group and ploidy. These differences may be further exaggerated by factors such as climate, soil type and system of farming.

Increased demands on grassland, with regard to early spring grass, mid-season production and extended grazing in the autumn, mean that care needs to be taken in the selection of suitable grass seed mixtures.

The aim when choosing a grass variety mix is to select a combination of three to four grass varieties with differing traits that, when used together, will produce a good dry matter yield from spring to autumn, and have a high sward density.

The Department of Agriculture's Recommended List of grass and clover varieties includes only those that have a proven record of performance over a period of years at several locations across the country, and are deemed most suitable for Irish conditions.

As such, this year's Recommended List is the 'bible' for growers to choose grass mixes.

Available to download from the Department of Agriculture website, varieties on the Recommended List are divided according to maturity or heading date and ploidy, and given scores for total yield, ground cover, spring growth, autumn growth, dry matter digestibility and water soluble carbohydrate levels.

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Perennial ryegrass varieties are grouped into three maturity groups -- early, intermediate and late -- on the basis of heading date or ear emergence.

The table (above) shows this year's Recommended List of intermediate and late heading perennial ryegrass varieties.

Early varieties

These head in the first half of May. Early perennials provide very good yields of early spring grazing and first-cut silage but stemmy regrowths in early summer can be a problem where long periods of uninterrupted growth are allowed to occur without grazing or cutting. In recent years, use of this group has declined in Ireland and sales are at a very low level.

Intermediate varieties

These types head in the second half of May and are ideal for producing high-quality silage cuts in late May and mid-July. Although not bulking up as soon as early perennial varieties, overall silage yields from intermediates are as good.

Varieties from this group are suited to a broad range of management systems, and should be included in any seed mixture.

Generally, their spring growth is not as good as for early perennials, but persistency is better.

Late varieties

These head in the first half of June and tend towards a prostrate (flat or horizontal) growth habit. They are characterised by high tiller densities, exhibit good ground cover, and are well suited to long-term grazing pastures.

Late varieties produce good-quality silage cuts in early June and late July, and are leafy in mid-summer.

Generally, their spring growth is not as good as for intermediates.

Under good grazing management, late perennials are extremely persistent and can survive very well for many years.

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