A study of the growth of subterranean clover (Trifolium subterraneum) in acid soil from Strathfieldsaye in East Gippsland

Legume-based pastures are widely used in the farming and pastoral regions of Australia. In southern Australia, subterranean clover has been the cornerstone of pasture improvement and increased crop and animal productivity since the 1930's and 1940's (Donald 1970). It has been estimated that as much as 80% of the present area of sown pasture in southern Australia may have been sown with subterranean clover (Donald 1970). The importance of subterranean clover is due to its ability to utilize atmospheric nitrogen and ultimately to improve soil fertility. Additionally, however, it provides high quality stock feed, is tolerant of grazing and possesses traits such as the ability to bury its seeds and also seed coat impermeability (hardseededness) which enable the plant to reappear reliably in pastures every year (Morley 1961). It is widely believed that the productivity of subterranean cloverbased pastures may have declined over the years since they were first established (Flemons and Siman 1970; Williams and David 1976; Osborne et al. 1978; Cregan et al. 1979; Williams 1980; Reeves 1981; Gillespie 1983; Evans and Hochman 1984). The cause of this 'decline' has been variously attributed to increased cropping, incidence of diseases and pests, poor grazing management (e.g. Cregan 1981; Gillespie 1983), but also has been associated with decreasing pH of soil under the pastures (e.g. Cook 1939; Donald and Williams 1954; Russell 1960; Watson 1969; Barrow 1969; Flemons and Siman 1970; Kohn et al. 1977; Williams 1980; Bromfield et al. 1983a). This thesis is concerned with a study of the growth of subterranean clover in acid soil from 'Strathfieldsaye' at Stratford, in the East Gippsland region of Victoria. The soil was taken from beneath a legume based pasture in which subterranean clover represented only a small proportion of the plants in the pasture. This situation was regarded as undesirable. The study was initiated because it was considered possible that the very low pH of the soil may have contributed to the low occurrence of subterranean clover in the pasture.