Less-Favoured Areas of Europe 1992

1. Less-Favoured Areas of Europe 1992

2. BackgroundHill and upland farming utilises 48% of UK agricultural landCarries 12.2 million ewes and 1.2 million suckler cows, 60% of the UK total

3. Government policy for the LFAs aims to:Ensure the continuation of livestock farming thereby helping to maintain viable upland communitiesConserve landscape and wildlife habitats

4. AREA OF LFA’S IN GRASSLAND AND ROUGH GRAZINGS Grassland Rough Grazing M Ha % M Ha % WALES 0.9 64 0.5 36 SCOTLAND 1.6 28 4.2 72 N. IRELAND 0.6 75 0.2 25 ENGLAND 0.6 33 1.2 67 UK 3.7 38 6.1 62

5. Support for viable upland communities Subsidy Schemes £15.00 per ewe Environmental enhancement Sustainable production Maximising Production

6. White clover use in the Uplands To improve the efficiency and cost effectiveness of upland livestock farming by improving the reliability of grass – legume pastures

7. Importance of Clover • Good ryegrass/white clover sward fixes the equivalent to 150 kg N ha-1 (Newbold, 1982) range 50-350 kg N ha-1. • Clover has twice as much protein as grass. • Much higher intake from clover and grass/clover swards (20% greater intake Thompson, 1984) and less chewing energy required (Penning et al., 1991). • Easily digestible cell walls. Faster particle degradation in the rumen (Moseley and Jones, 1984). • Complimentary growth curve to grass- spreads production • Particularly good for fattening lambs during the latter part of the summer.

8. Complementary Growth rhythms of Grass and Clover Grass/clover swards will produce 10-12 t/ha DM

9. White clover gives high post-weaning lamb growth rates 45% Increase in lamb growth rate (Vipond et al., 1993)

10. Lamb performance Pre-Weaning Grass +Clover Grass Lamb performance Post-Weaning Grass +Clover Grass

11. Total annual production of lamb Stocking rate on Grass/clover swards was 82% of that on grass-only swards. Lamb output was similar from the two sward types Grass + 150 kgN/ha Grass +Clover

12. Upland pastures contain less than 5% White clover Why is this ? The Upland environment is hard on white clover

13. The Upland environment: Cool Shorter growing season, does not attain optimum growth temperature for clover. Soils Upland soils are peaty with low pH and phosphorus status (affects N fixation). Less depth of soil in the uplands therefore subjected to periodic waterlogging and drought. Cold Colder winter temperatures means that winter survival and spring growth become more important. ManagementUpland swards are generally grazed by sheep, survival of clover under sheep grazing is problematical.

14. Soils Substantial quantities of N are bound up in Upland soils but availability is limited thus; a starter dressing of fertilizer N is recommended at a rate of 60-90kgN/ha to encourage establishment (Haystead and Marriott, 1979) Clover requires adequate P status for optimum growth. Estimates vary from 2-4 g P/kg DM. P applied to Grass/clover swards generally boosts white clover content. P availability declines with increasing pH. Vesicular Arbuscular Mycorrhizae increase P uptake by white clover in P-deficient soils. In addition to increasing P uptake they may also provide a bioprotection role against root pathogens and also make plants more tolerant of abiotic stresses too (Scullion et al,. 1998) There is scope for selecting genotypes for improved tolerance to low P and enhanced VAM associations.

15. Rhizobia leguminosarum bv. Trifolii • Soil acidity is known to have major effects on the rhizobium-white clover relationship affecting rhizobium; • survival, multiplication, infection of the root and nodule dvelopment. • pH of upland soils should be adjusted to pH 5.0 or above as this ensures low soil aluminium and manganese. • Peaty upland soils often contain low levels of Rhizobia or ineffective strains (Newbold et al., 1982) and inoculation with suitable rhizobia has been shown to have a substantial effect (Mytton and Hughes, 1984) • S.184 white clover was surface seeded into natural molinia pasture on wet stagnogley soil containing no indigenous Rhizobium trifolii. Seedlings were spray inoculated after emergence with each of three strains of R. trifolii. The best of these treatments produced an eight-fold improvement in dry matter in the seeding year, followed by a 28% improvement in the following year.

16. Sowing grass/white clover in the uplands - recipe for success • Soil pH must be raised by liming to at least 5.5 • 40-60 kg P and 80-100 kg K added per hectare each year • Starter dressing of 50 kg N in the seed bed • Sow grasses at 25-30 kg seed per hectare • Sow clover at 3 kg seed per hectare • Inoculation with rhizobia (essential in peaty soils) • Limit cultivation as far as possible • Sow as early as possible (April or May) • Graze new pastures lightly with rest periods to aid development of white clover • Maintenance dressings of lime and fertilizer required • Minimum cultivation techniques exist and provide a low cost alternative for improving the efficiency of upland pastures

17. Choice of suitable white clover cultivars is vitally important White clover cultivars for the uplands must be selected for their specific use Sheep grazing Small-leafed cultivars such as S184, Gwenda and AberCrest (new AberAce) Mixed or Small to medium-leafed cultivars or mixtures cattle Grazing of both types (Menna, AberHerald and AberDai) But even within a leaf size class differences in animal production can be substantial

18. Lamb Production (kg/ha) 1989-1991

19. New white clover cultivars for intensive sheep grazing New selection from welsh upland environment

20. Even when we do all this, fluctuations in clover content still occur Clover declines occur in new reseeds and older pastures alike They occur on a 3-4 year cycle Clover declines have a deleterious effect on animal production

21. White Clover Declines - New reseeds

22. White Clover Declines - Older pastures CaPK

23. Lamb output to weaning (kg/ha) from CaPK and CaPKN (150 kgN/ha) swards. Bronydd Mawr 1991-1995 Treatment Year1 Year2 Year3 Year4 Year5 CaPK 277 552 444 475 489 CapKN 351 586 485 566 643 LSD 42.7 94.0 72.7 43.9 46.2 P <0.01 NS NS <0.01 <0.001 Clover Decline

24. Sward height guidelines for sheep Lambs Ewes The above guidelines have been formulated against a background of knowledge concerning the physiology of grass growth under grazing and much of the evaluation of SSH guidelines has been carried out on swards dominated by perennial ryegrass. Grass/ clover swards are also managed in this way even though they rely on a high clover content to optimise the benefit of nitrogen fixation and superior feeding value of the legume.

25. Clearly clover declines or crashes are a feature of swards managed in this way and cause instability in the system. Although the clover plant seems to be able to adapt to the SSH guidelines for sheep grazing, strict adherence causes the white clover component to cycle in an unacceptable way WHY?

26. Mechanisms of coexistence operating in grass/clover mixtures have received intense study in recent years (Thornley et al., 1995; Schwinning and Parsons, 1996 a & b) in an effort to explain the fluctuations in sward clover content observed in long-term studies (Stewart, 1988; Tyson et al., 1990; Fothergill et al., 1996). The majority of models proposed have a common key element of a nitrogen-based competitive trade-off between grass and clover. In conditions of low nitrogen, clover has a high relative growth rateand can compete effectively with grass as it can complement mineral nitrogen uptake with N fixation. Under high nitrogen conditions, grass has a superior relative growth rate and demonstrates a competitive advantage over clover (Davidson and Robson, 1985).

27. Clover development and Morphology Once the clover seed is sown germination takes place quite quickly and produces a seedling with a spade-like first leaf. All subsequent leaves have the well-known ‘trifoliate’ shape. The seedling develops into a small plant with a central taproot and a short vertical stem. Lateral stolons develop from the lower nodes of the vertical stem and this stage is known as the ‘rosette’ stage. This is an important stage in clover establishment as seedling size and age affects the ability of clover to withstand low temperatures. As the terminal bud of each stolon (creeping stem) grows each node that is added has the potential to support a new leaf, two nodal roots and an axillary bud that can develop into either a stolon branch or a flower.

28. Clover development and Morphology During this phase stolons and branches are developing rapidly creating a large inter-connected plant that can spread swiftly through the sward accessing sites favourable for it’s development. The main taproot of a clover plant only survives for 12-18 months in the field and once this is lost the integrity of the clover plant is compromised and the plant breaks into smaller, independent plant units. This is the state of most of our grass/clover swards, stolon survival is the principal means of clover persistence in pastures and there are clear cyclic patterns in the development of the white clover plant throughout the year.

29. Clover development and Morphology During the winter the white clover plant fragments to create a spring/early summer population dominated by a large number of small, simple structured plants. After mid-summer the clover plants begin to increase in size and complexity and this growth of individual plants is also associated with an increase in stolon thickness. Large plants with thick stolons over-winter more successfully and thus this late summer phase is important for the maintenance of clover within swards. The amount of stolon and number of buds that exist in the spring determines the yield potential for the following summer.

30. Clover development and Morphology Management interacts strongly with this annual pattern of clover development and this is where the 4cm sward height guidelines for sheep grazing come into conflict with the needs of the clover plant. If swards are constantly grazed to 4cm or 4cm rising to 6cm at weaning, productivity and stocking rate will be high for the first 2 years of the swards life. However even though the swards will visually contain a large amount of clover the grazing regime interrupts the late summer increase in plant size and deflects the population of plants into a spiral of decline. The clover population now contains a very large number of extremely small simple structured plants. So small in fact that no further fragmentation can take place without plant death occurring. This is how the so-called ‘clover crashes’ occur.

31. Clover development and Morphology Clover is a perennial plant demonstrating a high degree of clonal integration. Some clover cultivars can even exhibit different growth strategies depending on supply of nutrients (Fothergill et al., in press). Large plants show plant plasticity and can compete with grass As the plant breaks up the benefits of clonal integration are lost and Intra-specific competition increases. This is the most severe form of competition and hastens the plant size decline.

32. The Remedy The plant populations must be manipulated to reduce both Intra-specific and Inter-specific competition • Select compatible combinations of grass and clover • Stagger the sowing of white clover over 2-3 years to create a population of white clover plants of varied size and age. • Be prepared to rest grass/white clover swards during the latter part of the summer to allow plants to build up in size

33. White Clover Crashes - Clover plant morphology Clover decline Compensation phase

34. Rosette plants Stoloniferous plants (Tap root forms) (Tap root decay) Late season silage cut Seedlings Large plants (Winter causes plants to break up) Continuous grazing Germination Clover Crash Increasing proportion of small plants Seeds (Continuous grazing restricts increase in plant size ) Eventually stolon thickness is reduced