Agroscope, Institute for Plant Production Sciences IPS, 1260 Nyon, Switzerland

Development of grass/white clover swards under rotational and continuous grazing with steers

Dynamics of botanical composition of four grass/white clover seed mixtures either grazed rotationally or continuously with steers were measured during four year The grazing system had little effect on the botanical composition of the swards. Perennial ryegrass was the main grass with 60 – 70 %. Arion, the first Swiss perennial ryegrass cultivar proved to be especially competitive. Only the botanical composition of the seed mixture with Italian ryegrass changed significantly. The part of Italian ryegrass decreased and was replaced by Perennial ryegrass and Kentucky bluegrass. The average white clover content decreased from 28 to 12 % during the four years.<br>Grazing management had an important influence on tiller populations. The tiller density was 62 % higher under continuous grazing. This was associated with an increased root mass (6010 vs 5432 kg DM/ha). The grazing system had little effect on the vertical distribution of the roots in the soil.

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