Grazing to Promote Red Clover
27 May 2024
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Last month, we discussed how appropriate grazing to promote white clover is based on maintaining short pasture swards, 4-6cm set stocked or 8-10cm entry with 4cm residuals on rotation, to maintain light levels and photosynthesis for low growing white clover plants and prevent grass dominance and shading out of clover. This month, we’ll be looking at red clover.
Red clover, with its prostrate growth habit and crown growing point is a very different plant to white clover meaning it requires different grazing management to promote its persistency in swards.
Growth Habit
Shown below, white clover has a multi-branched creeping stem called a stolon from which it grows new leaves, roots (containing the N fixation nodules) and flowers. This makes white clover grazing tolerant, with a persistent lifespan in well managed swards. Its low growth habit dictates the need to maintain short grazing covers to promote it.
Red clover, shown below, meanwhile has a single growing point, the crown which stores nutrients and from which stems and a deep tap root grow from. Again, unlike white clover, red clover has an upright growth habit allowing red clover to be situated higher in the pasture canopy to capture sunlight and photosynthesise.
Differences in physiology and growth habitat mean that red clover is capable of higher yields (10-14 tDM/ha), drought tolerance and nitrogen fixation (150-250 kgN/ha) but is much less grazing tolerant. It normally lasts 3-4 years but with newer varieties and effective grazing and cutting management it can last 4-5 years. Only growing from the crown, if this is damaged by machinery or grazing, the plant will die meaning sward persistency will be poor.
Red Clover
White Clover
Infographic credit: AHDB
Grazing Management
Red clover is most commonly grown with a companion grass for high quality multi-cut silage production followed by aftermath grazing, generally with lambs, where the recommended cutting height is 7-8cm to prevent damage to the crown.
Aftermath grazing of red clover is often set stocked where the recommendation is to not over stock and maintain covers above 6cm, again to protect the crown and maintain leaf area for photosynthesis.
Red clover dominant swards for grazing only and herbal leys containing red clover are becoming more common. In such swards, grazed all season, rotational grazing is essential if we want to promote persistency by:
- Managing grazing heights, to prevent damage to the crown, maintain leaf area for photosynthesis and allow sufficient rest between grazing to build energy reserves in the crown before the next grazing.
- Prevent selective grazing leading to over grazing of red clover in a mixed sward. Particularly in herbal ley swards or when added to conventional grazing mixes where composition of red clover is low, it can quickly become grazed out.
Plan the rotational grazing system to incorporate a longer rest (30 days in spring and summer) than grass white clover swards to build covers and energy reserves to allow recovery and quick regrowth following subsequent grazing round. Graze down to a higher residual of 6cm to prevent damage to the crown and maintain leaf area.
These targets are also beneficial for herbs, such as chicory and plantain, and other legumes such as birds’ foot-trefoil and lucerne benefiting the persistency of herbal leys. It should be noted however that longer rests with higher grazing heights and residuals will mean fast growing grasses such as ryegrass will not be managed optimally for quality with greater build up of dead and stem material.
For this reason, monoculture red clover and herbal leys without grass (or low inclusion and with less dominant grasses) are easier to manage for production whilst promoting persistency of red clover and herbs. Where grass is dominant in a sward, grazing management may need to focus on grass quality with shorter rotation eg 21 day rest in the summer but accepting that persistency of red clover will be poorer.
Recommendations for Red Clover
Grazing of red clover swards in the winter should be avoided, with grazing in the autumn ceased once ground conditions become too wet so as to prevent poaching and damage to the crown and loss of plants. Risk of bloat is also increased when grazing in wet conditions. Compaction is also more likely to occur in more open swards which will impact production of the sward the following year. Overwinter the crop at 4-6cm to maintain some leaf area.
It is recommended that breeding ewes do not graze red clover swards from 6 weeks-pre to 6 weeks post tupping due to risk of phytoestrogens within the plant causing infertility. For this reason, along with recommendation that swards are not grazed late into the season or winter, this means that it is often not appropriate to have red clover within the entire grazing platform. The optimal or maximum percentage of a farm being dependent on rainfall and soil type as well as the balance of different stock classes on a given farm.
Daniel Stout, SAC Sheep and Grassland Specialist, SAC Consulting
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