Density ofTrifolium repensplants in mixed swards under intensive grazing by sheep

SUMMARY Densities of physiologically independent plants of white clover were studied in New Zealand in pastures stocked at 22·5 ewes plus lambs/ha by set stocking, rotational grazing or a combination of both systems. Plants were sampled once a month for 1 year (1984/85) by taking turves and washing out the plants. Numbers of growing points and stolon dry weight per plant were obtained. At each sampling fifty, 50 mm diameter pasture plugs were taken from each sward and growing point density and stolon mass/m 2 of white clover were measured. The density of white clover plants in the swards was estimated on the basis of both stolon dry weight and number of growing points. The two estimates gave similar results. There was a trend of lowest densities in set-stocked pastures (334/m 2 ), intermediate densities in combination management pastures (431/m 2 ) and highest densities in the rotationally grazed pastures (553/m 2 ). The overall mean density of white clover plants was 439/m 2 and the range was 193–811/m 2 . The structure of swards under the three systems of grazing differed and this was considered to contribute towards the variation in density of white clover plants in the various swards.