Development, removal, and death of white clover leaves under 3 grazing managements in hill country

The development and fate of white clover leaves in hill country swards under each of 3 grazing managements (set stocking or rotational grazing with sheep, rotational grazing with cattle) were studied for 16 months. Managements did not consistently influence the rate at which leaves matured. Maximum individual leaf areas were reached in 9–11 days in summer and 22–28 days in winter. Over the entire observation period, 61–65% of leaves produced were removed by stock. Differences between managements were relatively small, except in winter when long rotations (63–70 days) allowed considerable leaf death between grazings in the rotational treatments. Over all, the number of leaves per stolon was greater under cattle than sheep grazing (3.05 v. 2.49–2.78) because of longer defoliation intervals in some seasons. However, when defoliation intervals were similar between managements, leaf number differences largely disappeared. Differences in defoliation patterns between managements were not considered large enough to cause substantial differences in plant performance, though greater leaf numbers per stolon under cattle grazing offer a partial explanation for the better clover growth observed under this treatment. The results also demonstrate that, despite high stocking rates, none of the managements were likely to have restricted assimilate supply through excessive leaf removal, as leaves were able to export assimilate for an estimated mean period of 15–17 days before being removed.