Plant productivity and persistence in mixed pastures containing lucerne at a range of densities with subterranean clover or phalaris

Abstract

Lucerne (Medicago sativa cv. Hunter River) was sown at three densities (rows spaced 17.5, 35 and 52.5 cm apart) in factorial combination with each of three cultivars of subterranean clover (Trifolium subterraneum cw. Geraldton, Seaton Park and Woogenellup) and two of phalaris (a summer-dormant selection of P. aquatics, and a P. aquatica-P. arundinacea hybrid). All three clover cultivars were included in the lucerne-phalaris swards. After the establishment year, plant productivity and persistence in these mixtures were assessed under rotational grazing over the next three years. Lucerne density had little effect on the total seasonal or annual productivity of the swards. Lucerne grew and survived best with Geraldton clover and worst with the phalaris hybrid; total pasture yields reflected these differences in summer (two occasions) or autumn (one occasion) when lucerne was the dominant component. In winter, when lucerne grew slowly, the cultivar of clover was an important factor influencing total production. A mixed sward of lucerne and Seaton Park clover grew as well as or better than the other mixtures in winter, and occasionally in summer-autumn it was more productive than lucerne-phalaris, Seaton Park persisted with lucerne better than did any other companion plant.