Leaving Certificate Agricultural Science

1. Leaving Certificate Agricultural Science Introduction to Grassland

2. Introduction • Grassland occupies 70% of the world’s agricultural land, making it the world’s most important crop. • In Ireland, grass provides 70 – 80% of our cattle’s feed requirements and over 90% of our sheep’s. • Approximately 90% of the farmed land area in the country is devoted to grassland and is the primary resource for almost all of our agricultural output.

3. Advantages of Grassland • Reduced feed costs • Reduced labour input • Reduced slurry acculumulation • Increased animal performance • Natural diet of ruminants • Reduction of input costs

4. Categories of Grassland • There are three main categories of grassland. Rough Mountain and Hill Grazing: • More appropriately called grazing than grassland as most of the land is taken up with heather, gorse, bracken and scrub rather than grasses. • It is characterised by large range in botanical composition, low stocking rates and low production. • The land is usually acidic or peaty and generally stony. • It can therefore be very difficult or impossible to cultivate.

6. Categories of Grassland - 2 Permanent Grassland • This is grassland that is never ploughed. • It is different from Hill Grazing because it is dominated by perennial grasses and scrub, and trees are rare. • It again displays a large range in botanical composition from highly productive grasses to clover to highly unproductive weeds like thistle and dock. • Generally permanent grassland is more productive than mountain and hill grazing areas and is also more highly stocked.

8. Categories of Grassland Leys • These are grassland areas sown by farmers which display the following characteristics: • Little variability in botanical composition • High stocking rates • High levels of production. • Leys are associated with good farm practices and high levels of management and are re-sown and re-seeded regularly.

10. Grassland Distribution • Grass dominates most of the land in nearly all the counties in Ireland. • In Munster, Ulster and Connacht it can be up to 90% of all agricultural land. • In the south – east it is only about 75%. Why? • The following table shows the relative amounts of grassland in Ireland.

11. Grassland Distribution - 2

12. Grassland Ecology • The natural vegetation in Ireland is deciduous forest. • This basically means that if all agricultural and industrial activity stopped, the land would eventually return to forest. • The stages of progression are as follows: • Bare Soil • Grasses • Shrubs (Bramble, hawthorn and Blackthorn) • Forest species like Oak, Ash, Birch and other trees which eliminate shrubs by their shading effect.

13. Grassland Ecology - 2 • Intensive grazing prevents this series of activities to take place. • This is because grass species can regenerate from points below the grazing level. • If grazing was reduced or stopped, shrubs would take over and then eventually trees. • This is important as the farmer must manage his / her grassland so as to ensure that unwanted shrubs don’t take over the area.

14. Growth of the Grass plant • The grass plant has three leaves • When a fourth leaf appears, the 1st leaf near the base of the plant starts to die back and wither. Later when the fifth leaf appears, the 2nd leaf next starts to wither away also. The pattern is that two leaves are always functioning • One leaf is always emerging and one is always dying • The grass sward should be grazed at the third leaf stage when it is at a height of 10 – 12 cm. it should be grazed down to a height of 3 – 4 cm.

15. If the sward is not grazed until the grass is taller than the 5th leaf stage, the first two leaves that are decaying will leave a white base to the remaining grazing sward and it will be slow to recover. The grass plant has an amazing ability to recover after grazing or cutting. In the months of April and May, this can be less than 21 days. The regrowth of the grass plant is due to secondary tillers which are shoots that develop from the base of the stem of the first or primary tiller. Constant cutting of grass stimulates a lot of tillering

16. Grass regrowth for the following season • The success of grass regeneration and tiller growth commences in late October, i.e. 60 days prior to the shortest day. Grazing should cease at this stage to allow for the growth of roots which is more vigorous over the winter • Autumn tillers initially have a vegetative phase but after winter frost they change to the flowering phase, leading to a huge spring growth

17. In early spring, 60 days after the shortest day, grass growth commences. Soil temperature must reach 6oC before this happens As the first leaves emerge photosynthesis gets under way Spring grass in highly nutritious in both protein and sugars and has a DMD in excess of 80%

18. Important Grassland Species • 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*

19. Important Grassland Species - 2 Permanent Grassland: • Bent Grasses* • Fescues* • Meadow Grasses* • Cocksfoot* • Meadow Fescue* • Timothy* • Perennial Ryegrass*** • White Clover**

20. Important Grassland Species - 3 Leys: • Cocksfoot* • Timothy* • Perennial Ryegrass*** • Short Duration Ryegrasses*** • White Clover** • Red Clover** • The asterisks determine the palatability and productivity of the species.

21. Grass Rating • 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. • Productivityrefers 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.

22. Grass Rating - 2 • Palatabilityrefers 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.

23. Grass rating 3 • Digestibilityis 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. • Dry matter contains the main constituents needed by the animal namely soluble carbohydrates in the form of starches and sugars, proteins, fats, vitamins, minerals and fibre. • Soluble carbohydrates are considered to be 100% digestible, protein 80% and cellulose 70% with fibre being the least digestible at 35%

24. Digestibility of grass varies throughout the grass’s year also. The stage of growth affects digestibility – when growth is in vegetative stage, there is a high concentration of carbohydrates which results in a high DMD. As the grass grows taller and begins to produce flowering stems, the carbohydrates are converted into cellulose which reduces the DMD. Before flowering the DMD may be 80 – 90%, and after flowering as little as 50%. The grass species – perennial rye grass is superior in terms of DMD

25. Dry Matter • Dry Matter: the matter remaining in a sample of food after the water has been removed. Abbreviated at DM • Dry Matter Digestibility (DMD): the amount (percentage) of dry matter that can be digested by an animal • Dry Matter Intake (DMI): The amount of feed an animal consumes, excluding its water content

27. Perennial Ryegrass • Perennial Ryegrass is a persistent, aggressive, dominant grass. • It will take over a sward if: • Fertility Levels are high • 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.

29. Perennial ryegrass

31. Italian Ryegrass • 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.

34. Clover • 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 (Nitrates). • 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.

38. Advantages of Red and White Clover

39. Other Important Grass Species • 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. • Below are the inflorescence of a) Timothy, b) Meadow Fescue, c) Cocksfoot and d) Meadow Grass

41. Timothy Meadow Grass

42. Meadow Fescue

43. Cocksfoot

44. Seed Mixtures • 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.

45. Seed Mixtures - 2 • 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.

46. Heading dates • The heading date of a grass species is the time when the ear emerges on the grass plant. • Grass are categorised as follows

47. Seed Mixture for Grazing • This may include a no of strains of perennial ryegrass of early, intermediate and late heading varieties so as there is grass from spring to autumn • Advantages • Constant supply of grass over the grazing season • Always a fresh supply of leafy grass with a high DMD value • Won’t be a dip in production levels at any point in the grazing season • Whole sward won’t go stemmy at same time leaving unpalatable and poor quality grass

48. Grass seed mixture for grazing • 50% late perennial ryegrass • 40% medium-late perennial ryegrass • 10% Italian ryegrass • 2 Kg white clover/ha

49. Seed Mixtures for Silage • All of the grass should have a similar heading date, as grass growth will be uniform • A seed mixture is used with only one strain of grass or a no of strains of the same type of grass with similar heading dates • As a result all of the grass is ready for silage at the same time.

50. Grass seed mixtures for silage • 50% mid perennial ryegrass • 20% late perennial ryegrass • 20% Italian ryegrass • 10% red clover