The benefits of including white clover in swards has been known for a long time, with clover based leys being as productive as those receiving 200 kg of Nitrogen per hectare. With the growing interest in herbal or diverse swards more research at the University College Dublin showed the benefits of introducing up to 6 different species into a sward.
Current research being carried out by the University of Reading including a mix of up to 16 species of grass legumes and herbs in the ley has shown that these swards are not only as productive as swards receiving up to 250 kg/hectare of Nitrogen, but more importantly, the animal performance in this trial is showing that the growth rates of steers in this trial were similar to those on the high input N swards.
The benefits from the increased diversity of species include more drought tolerance and improved palatability and reduced fertiliser inputs, improved flexibility in the length of the grazing rotation, compared to simple swards. Herbal leys are often more persistent and less likely to become infested by weed species as there is greater ground cover.
With the large number of species in the seed mix it is difficult to predict which species will establish although in some soils it is possible to predict which species will not. For example, Sainfoin is very unlikely to establish on heavy acid soils.
The introduction of non-ryegrass grasses into swards enables longer rotations from mid-summer onwards as these grasses do not go into a reproductive phase and simply continue producing more leaves. The palatability of legumes deteriorates more slowly after the onset of flowering when compared to ryegrass.
Leaving a high residual sward means that there is more trampling of material which is returned to the soil feeding the soil biology and improving soil fertility.
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