Less-Favoured Areas of Europe 1992

Background

Hill and upland farming utilises 48% of UK agricultural land

Carries 12.2 million ewes and 1.2 million suckler cows, 60% of the UK

total

Government policy for the LFAs aims to:

Ensure the continuation of livestock farming thereby helping to maintain

viable upland communities

Conserve landscape and wildlife habitats

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

Support for viable upland communities

Environmental enhancement

Sustainable production

Maximising Production

Subsidy Schemes £15.00 per ewe

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

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.

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% Y

ield

April May June July Aug. Sept. Oct.Grass

Grass Clover

Complementary Growth rhythms of Grass and Clover

Grass/clover swards will produce 10-12 t/ha DM

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Tetraploid +180 kg N/ha Tetraploid + clover

White clover gives high post-weaning lamb growth rates

45% Increase in lamb growth rate (Vipond et al., 1993)

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Lamb performance Pre-Weaning

Lamb performance Post-Weaning

GrassGrass

+Clover

GrassGrass

+Clover

0100200300400500600700800

An

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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

Upland pastures contain less than 5% White clover

Why is this ?

The Upland environment is hard on white clover

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.

Management Upland swardsare generally grazed by sheep, survival of clover under sheep grazing is problematical.

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.

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.

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

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 mixturescattle Grazing of both types (Menna, AberHerald and

AberDai)

But even within a leaf size class differences in animal production can be substantial

Lamb Production (kg/ha) 1989-1991

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Lowland Upland

AC 3351 Huia S184

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Sto

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AberDal

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Ac 58

AberCre

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.S18

4

Gwenda

Deman

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Alber

ta

Grass

Only

Small leaf Clovers. Spring 1999 Stolon abundance

LSD = 106.7

New white clover cultivars for intensive sheep grazing

New selection from welsh upland environment

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

White Clover Declines - New reseeds

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White Clover Declines - Older pastures

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CaPK

Treatment Year1 Year2 Year3 Year4 Year5

CaPK 277 552 444 475 489CapKN 351 586 485 566 643LSD 42.7 94.0 72.7 43.9 46.2P <0.01 NS NS <0.01 <0.001

Lamb output to weaning (kg/ha) from CaPK and CaPKN (150 kgN/ha)

swards. Bronydd Mawr 1991-1995

Clover Decline

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Sward height guidelines for sheep

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.

Lambs

Ewes

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?

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 rate and 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).

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.

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.

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.

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.

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.

Clover development and Morphology

The plant populations must be manipulated to reduce both Intra-specific and Inter-specific competition

The Remedy

•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

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White Clover Crashes - Clover plant morphology

Compensation phase

Clover decline

Seeds

Germination

Seedlings

Rosette plants Stoloniferous plants

(Tap root decay)

Large plants

(Winter causes plants to break up)

Increasing proportion of small plants

(Continuous grazing restricts increase in

plant size )

Eventually stolon thickness is reduced

Continuous

grazing

Late season silage cut

(Tap root forms)

Clover

Crash

Stolon Branch Flower head

Terminal bud

Axillary budsRoots and Nodules

Nodes

Morphology of white clover