Red Clover

Red clover-based swards on organic farms

Red clover silage swards can meet the forage requirements of an organic farm whilst improving the protein content and overall feeding value of the winter forage.

Red clover is better suited to silage production than white clover because of its much more erect growth habit and its significantly higher forage yields.

It will not persist if grazed more frequently than every 30 days due to a combination of excessive foliage removal and plant crown damage by hoof trampling. Typical persistence is two to three years, that is two full harvest years after the establishment year.

Red clover can also be used as a green manure crop on cropping and horticultural units. It is particularly valuable for building soil fertility once organic conversion has begun.

Benefits of red clover- based swards

Red clover silage has a high crude protein content of 16 percent to 20 percent and a ME content of 10 to 12MJ/KG DM, depending on the growth stage at cutting
Its better palatability compared to grass silage gives greater intakes, resulting in high levels of animal performance in terms of milk and protein yields or liveweight gain
Swards are relatively drought tolerant due to the deep rooting ability of red clover, and are winter hardy
Red clover is suitable as a break crop to improve soil structure and fertility, and as a supplier of organic matter
Lambs fatten very well on red clover grass aftermaths

Forage potential of red clover

Red clover will perform best on well drained, fertile soils with a pH of 6-6.5. Typical annual requirements (based on soil phosphate (P₂O₅) and potash (K₂O) indices of 2) for an annual yield of 12t DM/ha/year would be 100-150 KG P₂O₅ and 250-300 KG K₂O /ha.

Normally, 80-90 percent of the annual yield is obtained from two silage cuts completed by late July - early August. Slurry or well composted farmyard manure is applied in early spring and between cuts, weather and ground conditions permitting.

Cut the crop at the early bud stage around mid-late May and again in late July, depending on rate of regrowth in mid summer. Rest the sward in September and cut or graze off herbage in October, if this can be achieved without poaching. This will encourage branching and should improve sward persistence over winter. Severe winter grazing may damage the plant crowns directly by physical damage and indirectly through soil compaction.

Late flowering varieties are more tolerant of grazing, as they produce more buds from the plant crown. Lax grazing would be beneficial to red clover in mixed swards. Sheep can apply considerable grazing pressure as they selectively graze the red clover, especially where herbage density is low.

Establishing red clover

Choice of red clover varieties

Most varieties currently available are early flowering. These have two main growth flushes during the growing season and start growth in spring earlier than late flowering varieties.

Typical persistence is two to three years, that is two full harvest years after the establishment year. Provided the overall sward management is good and sufficient nutrients can be applied, timely renovation will result in swards rich in red clover for several years.

Varieties such as Merviot, Marcom and Kuhn have good yield and Sclerotinia resistance. The more recent variety, Milvus has improved productivity and persistence.

Varieties with a stoloniferous (creeping) growth habit are being developed in New Zealand to improve the tolerance to grazing.

Choice of variety is of less importance if the red clover is being grown simply as a green manure.

Choice of companion grass for red clover

Mixtures of red clover with grass will give higher total forage yield, dry matter content, water soluble carbohydrate concentration, digestibility and metabolisable energy, than red clover dominant stands. However mixtures will have lower protein content and lower levels of some minerals such as calcium and magnesium.

Competitive, short duration ryegrasses are the best companion grasses for clover. Variety combinations need to be selected on the expected duration of the sward within the land rotation.

Red clover grown as a green manure does not need a companion grass.

Hybrid ryegrasses, bred by crossing Italian and perennial ryegrasses, make very suitable companion grasses for red clover silage swards

Typical seed rates (kg/ha):-	red clover	grass
red clover only	12-15
clover dominant mixture	15	5
grass dominant mixture	7.5	22
as green manure crop	15-20

Notes:
- use Italian / Hybrid ryegrasses for less than three years duration
- use Hybrid / Perennial ryegrasses for more than three years duration

Guidelines for successful clover establishment

There are several ways of achieving red clover-rich grass swards:

Direct reseeding
Undersowing
Overseeding
Strip or slot seeding

Ensure that you:

test the soil and target Index 2 for phosphate, potash and pH = 6-6.5
sow from April to August
prepare a fine, firm and level seed bed
sow seed at 10-15 mm depth

Note:

Young red clover plants are not very competitive against weeds
Over the cutting season approximately 12t DM/ha (= 60 t/ha fresh) of clover/grass silage will remove 100-150KG/ha P2O5 and 250-300KG/ha K2O
Cattle slurry @ 22m3/ha (2000 gals/ac) with 1:1 dilution, provides 10KG N, 14KG P2O5 and 54KG K2O per ha, applied in the spring

Undersowing - can be useful for spring reseeds, using early maturing spring cereal varieties as the cover crop.

Overseeding - a range of methods are available for placing seed into a sward, such as direct drilling using the Vertikator, Einbock, power-harrowing or discing and harrowing ground and then broadcasting the seed.

Strip or slot seeding - existing swards can also be upgraded using this specialist technique, but can give variable results.

Alternatively, follow in immediately after a silage cut taken in July or August, when soil conditions are neither excessively wet nor dry.

Reseeding

All the basic principles for any reseeding operation must be considered, for example, adequate drainage, pH, fertility, and weed and pest control.

A routine programme of soil analysis to keep a check on soil fertility is worthwhile every three to five years.

Soil analysis should be carried out on any fields that are to be reseeded. Lime can be used to correct soil pH.

In addition to manure and slurry, some natural sources of phosphate and potash, such as ground rock phosphate and rock potash, can be used to maintain soil fertility.

Management of red clover

Weed control

In direct sown swards, topping or forage harvesting can control many annual weeds. Grazing when the grass is 10cm tall can provide a useful degree of control of annual weeds, for example, chickweed, hempnettle and redshank, and of ragwort in established swards.

However, care must be taken to avoid overgrazing and poaching, especially when soil conditions are wet. Periods of frost can provide an opportunity to graze with minimal damage.

Thistles do not survive long if repeatedly topped before flowering. Docks are the most difficult weeds to control in an organic system.

Making red clover silage

Red clover silage has a higher protein content and is often more palatable to cattle than grass silage. However, red clover is characterised by low dry matter and low water soluble carbohydrate contents and a high buffering capacity. As a result, it is more difficult to obtain a satisfactory fermentation with red clover than with all-grass silage.

It is advisable to wilt for 24-48 hours in dry conditions to achieve 25 percent dry matter content. This will also concentrate sugars to encourage a desirable fermentation and reduce silage effluent production. Overwilting can result in substantial leaf shatter and loss and it can be difficult to consolidate very dry material in the clamp.

Red clover wilted to 25 percent dry matter will often ensile effectively without an additive. However, where herbage is wet or where there is a very high proportion of red clover, an effective additive can be used to ensure a stable fermentation.

Molasses, inoculants and enzymes can be used within organic systems as silage additives.

Note that molasses used as a silage additive (or fed) must be organic itself.

When weather conditions do not allow for adequate fermentation, permission may be obtained from the organic sector bodies to use an acid additive.

Pest and disease control

A number of pests can attack clover plants, but routine control measures are not considered worthwhile.

Red clover is even more susceptible to leatherjackets than grasses, although it will eventually recover after most attacks.

Although a number of diseases can affect red clover, there are no routine recommendations for their control.

Animal problems associated with red clover

Although red clover based swards can promote better liveweight gain in cattle and sheep and greater milk production in dairy cows than grass swards, care must be taken in their utilistaion.

Breeding ewes should not be grazed on red clover, or fed red clover silage for a period of four weeks before and until four weeks after mating, to avoid any adverse effect of red clover oestrogens on lambing percentage. Lambs can be fattened very effectively on red clover silage aftermaths.

Bloat is a potential hazard when swards with a high red clover content are grazed. The risk can be reduced by feeding roughage, such as straw or hay, before turning out and if necessary during grazing.

Never allow hungry stock to gorge themselves on clover-rich pastures. Moving stock onto dry rather than wet pasture reduces the risk.

Affected animals may be treated with antifoaming agents such as proloxalene. In severe cases remove animals from clover swards and seek veterinary advice immediately.

Red clover as a green manure

Red clover grown as a green manure in a crop rotation will provide organic matter to the soil and nutrients, particularly nitrogen, for the following crop. Red clover green manures are usually put down for one to two years, often at the start of a farm conversion as a means of improving soil fertility. They have an important place in stockless arable and horticultural rotations.

Red clover green manure crops must be managed. Grazing is an option, but as animals are removed they will inevitably take nutrients with them. Topping as a means of mulching is a second option, particularly if livestock are not available or not wanted. The sward should be topped regularly to keep it relatively short and to avoid smothering the plants with a large mass of mulched material.

Alsike clover

Alsike clover could be an option for land which is too heavy, wet or acidic to support red clover. Like red clover the plant is short lived, generally being productive for two years. However, it sets seed freely and can regenerate from shed, ripe seed if it is allowed to mature during the season. It has an upright growth habit and is usually grown in mixtures with grasses, for example, Timothy, and other forage legumes. Like red clover it does not spread and so a good distribution of seedlings is vital from the outset. The seed is small so it should be sown no deeper than 10-15mm. There is little data on production but yields of up to 10.7t DM/ha in the first year and 7.7t DM/ha in the second year are reported from Great Britain. The feeding value is similar to red clover. It too can be used as a green manure crop.

Seed regulation

All seed sown on organic farms must be certified as organic. Organically produced seed is in short supply at present, but becoming more readily available each year. In the meantime, if sufficient suitable organic seed cannot be sourced, producers must request a prior derogation from their sector body to use untreated non-organic seed.

Contact for further information

Manus McHenry

Greenmount Campus, ANTRIM, BT41 4PU

Tel: (028) 9442 6642Mobile: 07717 732613

Email: manus.mchenry@dardni.gov.uk

April 2008

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