Between 200 and 300 species of grass exist in Ireland but only a small number are of any real importance to the farmer. Some of the common species found in the different types of grassland are shown below: Hill and Mountain Grazing: Heathers Purple Moor grass Bent Grasses* Sheep’s Fescue* Creeping Red Fescue* Meadow Grasses*
Leys: Cocksfoot* Timothy* Perennial Ryegrass*** Short Duration Ryegrasses*** White Clover** Red Clover** The asterisks determine the palatability and productivity of the species.
Grassland in Ireland is used solely for feeding livestock. Therefore the agricultural importance of any grassland is measured in three ways: Productivity, Palatability and Digestibility. Productivity refers to the ability of a grass to produce large amount of herbage. It also refers to the ability to respond to a fertiliser. Perennial ryegrass has the highest productivity while mat grasses have low productivity. Palatability refers to taste etc, in other words how appealing the grass is! Sheep and cattle are selective eaters and will only eat the most palatable grass.
Therefore the sward should be made up of appealing varieties. PRG and IRG are the most palatable grasses followed by cocksfoot. Digestibility is a rating of the ability of an animal to digest a certain feed. It is measured in terms of DMD (Dry Matter Digestibility) – how much of the dry matter the animal can digest. Digestibility of grass varies throughout the grass’s year also. Before flowering the DMD may be 80 – 90%, and after flowering as little as 50%.
Perennial Ryegrass is a persistent, aggressive, dominant grass. It will take over a sward if: 1.Fertility Levels are high 2.Grazing is extensive It is the most palatable, most digestible and most productive of the grass varieties. It is ideal for grazing and for silage. Makes up to 85% of the total grass seed sold each year to Irish Farmers. It has a shiny dark green colour, which gives the sward a glistening sheen.
Similar in appearance to perennial ryegrass but has awned seeds A more erect growth habit and less aggressive growth pattern. It is however the highest producing grass, nearly 20% more than perennial in the first year. In subsequent years it begins to die back. It is a biennial. It is ideal for early grazing or 3-4 cuts of silage.
Clovers are legumes which mean that they can fix Nitrogen. This generally means that they can change atmospheric Nitrogen into forms that the soils can absorb and use. Very high in protein. Therefore they are of huge importance to the farmer and they improve the quality of the sward and soil. However they can have a negative reaction to artificial fertilisers that contain Nitrogen. They also have deep roots and spread throughout the soil by stolons, which then inhibit weed growth.
While Perennial ryegrass, Italian ryegrass and clovers supersede all other grass species in seed sales each year, there are other important species. These include: Timothy, Cocksfoot, Meadow Fescue and Meadow Grasses. These were traditionally used many years ago but are still very important in permanent grasslands. Farmers should be able to recognise them and encourage their growth. Use your book for more detail on these varieties. Below are the inflorescence of a) Timothy, b) Meadow Fescue, c) Cocksfoot and d) Meadow Grass
Seed mixtures are very different for grassland as opposed to silage. In previous years it was usual practice to sow a number of different varieties as to have a uniform grass growth throughout the year. This has changed over the last number of years, towards mainly ryegrasses and clovers. This is mainly due to the emergence of new strains of perennial ryegrass, which have different peak growth times. Now seed mixtures for grazing have different strains of PRG, which have a range of heading dates.
This gives the following advantages: Encourages uniform growth patterns Ensures there is always young, leafy digestible grass available as feed. Makes grazing management easier – all the grass can’t go “stemmy” at the same time. For silage or hay, seed mixtures contain either strains with the same heading dates or seeds from the same strain only. This is to ensure that the entire sward comes to a head at the same time. This gives a sward that is all at the height of its digestibility when cut.