Incorporating white clover into grass swards

The benefits of including white clover in grass swards has been noted by several research trials carried out by Teagasc and other international research agencies.

The use of clover allows cows to eat more grass with less chemical nitrogen (N) application required.

White clover has rhizobia bacteria in its roots that can ‘fix’ N from the air, and this can then supply up to 50-200kg N/ha/year.

In frequently grazed swards (eight to ten times/year) up to 250kg N/ha/year can be fixed.

White clover

For clover to persist and contribute, it needs a soil pH of >6.3 and the soil phosphorus (P) and potassium (K) indexes need to be at three or greater.

The sward needs to be grazed every 18-21 days in mid-summer to allow sunlight to penetrate to the sward base where the stolons of the clover plant are growing.

Early June is an ideal time of the year to incorporate clover into a sward; with a full reseed, 3-5kg/ha of clover seed is required.

On fields that have been cut for silage, over-sowing is another option. This requires 4-6kg of white clover seed with two and a half bags of 0:7:30 or 0:10:20 per hectare.

Reduce fertiliser N application to give the clover a chance of establishing itself.

Roll the sward after sowing or apply 5,000gal/ha of dirty water to improve soil-to-seed contact.

Teagasc Moorepark trial

As part of the research into white clover swards, Teagasc Moorepark currently has three experimental treatments:

• Grass-only, receiving 225kg N/ha;
• Grass-white clover, receiving 150kg N/ha;
• Grass-white clover, receiving 150kg N/ha in an alternative N application strategy.

The results from the trial are outlined in the box below, these results are from the 2021 grazing season so far up until June 21, 2021.