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The rise in fertiliser prices is pushing many livestock farmers to make greater use of clover swards on farm.
Much has been said about the nitrogen-fixing properties that clover can provide, as well as being higher in protein, trace minerals and more digestible than ryegrass.
Under the right management, clover can provide nitrogen for plant growth as well as having a positive effect on livestock performance.
However, it cannot be over-stressed that to achieve these benefits, grassland management has to be top-class on farm.
On farms where swards are poorly managed, or soil fertility is low, do not assume clover will thrive and provide a viable solution to higher nitrogen prices this year, or in future.
So when it comes to managing clover in grazing and silage swards, outlined are 10 things to keep in mind.
1 Do I need to reseed to increase clover content?
Reseeding is a quick way to increase clover in swards, but it is not essential. Getting soil fertility right and a well-managed grazing system will naturally increase clover content also.
Clover needs soils at pH 6.0 to 6.5 and ideally at index 2, or above, for phosphate (P) and potash (K).
Spreading ground limestone takes four to six months to alter soil pH, so consider a granulated lime product for a quick-fix on soils below optimum pH levels.
White clover tillers out along the ground and can be easily shaded out by heavy grass covers. Therefore, grazing swards tight ensures clover plants are getting sunlight, helping them to tiller and increase their presence in swards.
Reseeding should never be deterred. However, weather depending, it can be take anywhere from six to 12 weeks from burning off a sward until a reseed is ready to graze.
Can farmers afford to take fields out of production for so long if they plan on reducing nitrogen applications this year?
2 Choosing the right clover
If a new clover sward is being established, choose a variety that suits the purpose of the sward.
Small leaf varieties have lower yields, but have a greater stolon density. This makes them suited to intensive grazing from sheep.
Medium and large leaf varieties are better suited to cattle grazing, while large varieties also suit silage systems.
White clovers are better suited to grazing, while red clovers perform better when included in silage swards but can be grazed with careful management.
3 Sowing clover
White clover seeds are extremely small and should be drilled between 5mm to 10mm deep, ideally using an air seeder that scratches the surface of the seed bed.
Always fill the seeder box in the field. By filling the seeder box in the yard, the vibrations when driving to the field can cause clover seeds to filter to the bottom of the hopper, resulting in a very uneven reseed.
Control weeds before reseeding as “clover-safe” spray options are limited.
When reseeding after ploughing, roll the seed bed before and after drilling.
If stitching in clover, choose an open sward, remove as much trash as possible, then apply lime as decaying grass can be acidic and hinder germination.
4 Rotational grazing
Clover swards perform best under rotational grazing. For white clover, graze down to a 4cm residual, then move stock on and allow the sward to regrow.
For red clover, graze down to 8cm then remove stock. The higher residual protects the crown of the plant. Red clover swards are best grazed in 24-hour allocations.
The rest period between each grazing should be slightly longer compared with perennial ryegrass at 20 to 25 days.
5 Reduce nitrogen use during summer and autumn
Clover growth increases from May onwards, so either cease or reduce fertiliser applications after this point to get the benefit of the plant’s nitrogen fixing potential.
Dig a few soil cores in the clover sward and examine the roots
6 Check the root nodules for fixing activity
Dig a few soil cores in the clover sward and examine the roots. Clover has nodules on the roots called rhizobia. If these nodules are actively-fixing nitrogen, they should be red or pink in colour.
7 Wilting silage
When cutting clover for silage, mow once the plant starts to flower, then wilt for 24 to 48 hours to raise dry matter to around 30%.
Ensiling clover at a low dry matter will lead to poor fermentation due to the higher nitrogen content in the plant.
The higher nitrogen levels in the plant will increase the forage’s protein content and it can turn red clover black when ensiled.
Red clover is a fragile plant when cut, so avoid tedding and raking as this causes the leaf to shatter.
As with grazing, leave a residual around 8cm high when cutting red clover for silage.
8 Reducing the bloat risk
Clover can increase the risk of bloat in livestock as the plant is easily digested. The risk is lower in spring when turning cattle out to grass, as clover is slow growing at this point in time.
The risk increases in summer, particularly if animals are not used to grazing clover swards, or animals enter a field in a fasted or hungry state.
Keep this in mind when bringing cattle in for routine handling. Return animals to the field ASAP. Offering some fibre or bloat oil in water troughs can lower the risk.
Turning hungry cattle into a wet clover sward should be avoided as again, this poses a higher risk of bloat.
When rotationally grazing cattle, it is important to move animals to the next paddock as soon as covers get low.
Don’t delay moving animals. When cattle are continuously grazing clover swards, the risk will be reduced.
9 Avoid winter grazing
Over-grazing clover can reduce the lifespan of the plant. Clover should not be poached at any stage of the year, but especially in winter.
With red clover, the crown will be damaged, making the plant susceptible to diseases such as sclerotinia.
Therefore, close off swards in late autumn once ground conditions get marginal and rest until spring.
10 Be wary of red clover on mixed grazing farms
If cattle and sheep graze the same land blocks, breeding ewes should stop grazing red clover swards at least six weeks before breeding starts and after it ends.
Red clover contains oestrogens that will impact on ewe fertility and, ultimately, stop ewes from cycling.
These oestrogens do not affect suckler cows.
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