Managing existing clover swards

Best practice grazing management is similar for grass-white clover swards and grass-only swards. Deirdre Hennessy, Teagasc Researcher talks here in a short video about Managing existing clover swards, mid-season fertiliser requirements, preventing bloat and more

Grazing Management Mid-season (April to July)

Best practice grazing management is similar for grass-white clover swards and grass-only swards. Flexibility and willingness to adapt to the conditions are important when managing grasswhite clover swards. Good grazing management is also important for increased persistence and production of white clover in grazed swards. In the mid season:

1. Maintain pre-grazing herbage mass between 1,300 and 1,600 kg DM/ha (8 to 10 cm)
2. Target post-grazing sward height of 4.0 cm

Fertiliser Requirements Mid Season

Chemical N fertiliser may be reduced on swards with good white clover content (≥ 25%).  The table below provides a guide to the potential to reducing chemical N application where there is a high proportion of clover in the sward.  As a rule of thumb, it is half the normal application rate.

Grazing management to prevent bloat

Bloat can be an issue in swards with high white clover content. Bloat can occur at any time of the year but it is more likely to occur in the second half of the year when white clover content in the sward is highest. Good grassland management can minimise and prevent the risk of bloat.

Bloat prevention

1. Avoid switching between grass-only and grass-white clover swards (as much as is possible).
2. Keep post-grazing sward height at 4 cm, not below.
3. When entering a grass-white clover paddock in risky conditions (high white clover content / hungry animals / wet morning / very lush pasture) provide a small area in the paddock for the first 2-3 hours after turn-out to prevent the initial gorging on white clover.
4. Provide anti-bloating agent in the water supply – starting the day prior to entering the risky paddock.
5. Check cows after initial turnout and regularly for first three hours of grazing during high risk periods.

Additional Notes

White clover has a poor competitive ability to absorb most soil nutrients compared to grass due to the different characteristics of the root systems of the two species. Perennial ryegrass has a denser longer, thinner and more finely branched root system compared to white clover. As a result, white clover is generally at a disadvantage when it comes to nutrient uptake from the soil.

Soil pH is critical for white clover development. White clover is more sensitive to lower soil pH than grass:

1. Soil pH should be greater than 6.3.
2. Low soil pH reduces soil nutrient availability for plant growth.
3. Low pH soils can be deficient in plant available calcium (Ca) and magnesium (Mg) which are necessary for rhizobia (N fixing bacteria) survival.
4. In low pH soils manganese (Mn) and aluminium (Al) toxicity can have a major effect on white clover development.
5. Formation of nodules for N fixation is reduced below soil pH 5.8.

White clover requires a minimum of soil Index 3 for P (5.1 – 8 mg/l) and K (101 – 150 mg/l).

Watch as Deirdre Hennesy, Teagasc talks about maintaining sward white clover in mid-season, in the video clip below

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