Search

Lucerne (alfalfa; Medicago sativa L.) is the key forage for grazing in dryland temperate regions around the world. While rotational grazing of lucerne is recommended, in southern Australia the intervals between grazing events are often chosen in an opportunistic manner, to meet livestock production targets and utilise excessive spring and summer growth. To assess whether the persistence of lucerne is sensitive to variations in rotational grazing management practice, we report on an experiment with four sheep grazing treatments that was conducted for 2.5 years, including three summers, in southern New South Wales. The grazing management treatments were a crash-grazing control, frequent grazing, feed-based rotational grazing and time-based rotational grazing, replicated four times. The number of grazing events, percentage of time under grazing, lucerne top dry matter (DM) at the beginning and end of grazing periods and plant density were measured. The results relating to number of grazing events, percentage of time grazing and DM removed during grazing indicated that four grazing practices had been achieved. The treatments all had significant periods of rest for at least 73% of time and were empirically different in their approach but resulted in similar grazing pressures, in terms of overall pasture removed during grazing. Nevertheless, there was little difference in lucerne densities between grazing treatments over the life of the experiment. We conclude that there is flexibility in the rotational management of grazed lucerne provided adequate rest periods are part of the management program. [ABSTRACT FROM AUTHOR]

Lucerne (Medicago sativa L.) persistence is important for farming systems in south east Australia. Defoliation of lucerne that is too frequent (arguably more than once every six weeks) reduces yield and accelerates stand decline. Three experiments were conducted in south east Australia (Burraja, New South Wales; Rutherglen and Hamilton, Victoria) to investigate different cutting regimes on lucerne persistence. At Burraja lucerne was cut 16 (lax) or 33 (severe) times over three years at different plant densities. At Rutherglen and Hamilton lucerne was cut every 21 days (short rotation), every 42 days (long rotation), when new shoots (2.5 cm long) emerged (new shoots) or cutting when new shoots emerged but allowing the lucerne to flower in autumn (new shoots flowering). It was hypothesised that the frequent cutting of lucerne would result in lower plant densities. At Burraja there was little difference between treatments at any density or assessment. At Hamilton, apart from the assessment in June 2016, there was no difference (p > 0.1) between treatments. At Rutherglen, there was no difference (p > 0.1) between treatments at any assessment although plant numbers declined in 2016 from waterlogging. The results provide evidence that lucerne has intrinsic mechanisms that protect it from cutting, often at short intervals, thus promoting its persistence over three to four-year periods. [ABSTRACT FROM AUTHOR]