White clover and herbs

There was very little clover in the swards on the unit at the start of conversion. A program of sward renovation was undertaken to improve the productivity of the swards which had previously received inorganic fertiliser. Swards were grazed hard or cut very close and the soil was loosened with a shakerator. Clover seed was stitched into the existing sward.

In fields where new grass was introduced along with clover a power harrow was used prior to stitching. Stitching in can be successfully carried out from after first cut silage until the end of August. This technique is used in preference to conventional ploughing and reseeding on the unit.

Conventional reseeding is carried out within the rotation on the unit. A firm seedbed and shallow sowing are essential when clover seed is used. It is important to sow by the end of August to enable the seedlings to be well established before the onset of winter.
Winter triticale in the two years prior to reseeding is being grown to control perennial weeds such as docks.

Seed sown on organic units must be certified as organic. The choice of clover variety is determined by the intended use of the sward. White clovers are classified according to leaf size: small, medium, large and very large.

Small leaved varieties survive best under intensive sheep grazing as they have a creeping growth habit. However, they can be expensive, and some varieties can, at times, be in short supply. A newer variety, Crusader, has been included in mixtures at Greenmount, as it grows well at both ends of the season.

Medium leaved varieties are generally tolerant of a wide range of conditions and should always be included in mixtures intended for all grazing use.

Large leaved varieties are for general purpose use and are best suited to rotational grazing by cattle or sheep or where some silage is taken.

Very large leaved varieties are high yielding but are least persistent under grazing and are best confined to hay or silage swards with only limited grazing use.

The best compromise is to use a mixture of clover varieties, half of which should be medium leaved. The remainder should be either small, medium or large leaved varieties depending on the intended sward use. Clover should be sown at about 5 KG/ha.

Intermediate and late heading Perennial Ryegrasses, including tetraploid varieties, are generally regarded as the best companion grasses for clover. When reseeding on heavy soils it may be worth replacing two to three KG of Perennial Ryegrass with Timothy. It is also likely that Meadow Fescue and other alternative grasses may well have a valuable place in white clover based swards.

The inclusion of herbs can also be considered. Many herbs will germinate and grow quite readily but can be difficult to maintain over time and add to the cost of the seed mixture. They can be sown throughout the field or in strips or corners of fields. Herbs provide a rich source of minerals to grazing livestock. Some contain high levels of condensed tannins which can help to control worms in grazing stock. Herbs sown on the Greenmount unit include chicory, ribwort, bird's foot trefoil, salad burnet, sheep's parsley and yarrow.

Slurry or farmyard manure is spread in Spring to encourage early growth. The aim is to maintain a soil index of 2 for phosphate and potash across the unit. When any forage rye in the rotation has been grazed, ewes and lambs move onto the clover swards. Springing cows are grazed on bare ground, behind the sheep. During spring the aim is to avoid under-grazing with store cattle and cows and calves. Broad leaved weeds are topped. In autumn the swards are not overgrazed and care is taken to avoid poaching. The ewes graze the unit during the winter which is beneficial to the clover swards.

Where possible silage and grazing fields are rotated. Two cuts of silage are usually taken. The aim is to wilt herbage to at least 25% dry matter before ensiling.

© DARD 2008