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Effects of methods of sowing on establishment of forage and pasture species

S. Khan, E.D. Carter and S. Pattison*

Agronomy and Biometry* Departments, Waite Agricultural Research Institute, The University of Adelaide, Glen Osmond, S.A. 5064

It is generally acknowledged that the pastures of both the cereal belt and the higher-rainfall areas in southern Australia have declined in productivity and quality in recent years through loss of legumes. At the Leura Conference of pasture specialists in December 1985 there was unanimous agreement that the most urgent task was to restore the legume status of these pastures (l). This paper summarizes some aspects of an ongoing research programme designed to assess various cost-effective methods of pasture establishment.

Methods

A drill plot experiment involving 8 factorial combinations of pre-sowing cultivation, sowing methods and post-sowing harrowing was commenced on loamy mallee soil at the Charlick Experiment Station at Strathalbyn in May 1988. Methods of sowing comprised:A = Uncultivated, broadcast, not harrowed;B = Uncultivated, broadcast, harrowed;C = Uncultivated, drilled, not harrowed;D = Uncultivated, drilled, harrowed;E = Cultivated, broadcast, not harrowed;F = Cultivated, broadcast, harrowed;G = Cultivated, drilled, not harrowed;H = Cultivated, drilled, harrowed. Subclover (Trifolium subterraneum) cv. Clare, balansa clover (Trifolium balansae) cv. Paradana, snail medic (Medicago scutellata) cv. Sava, and forage brassica cv. Simax were sown as a basal mixture (29kg/ha) along with 270kg/ha single superphosphate. Because it was distinct from all other species on site, Simax was used as an indicator of the efficacy of the various establishment methods. Plant number and yields of sown species were assessed 23 and 84 days after emergence, respectively.

Results and discussion.

Maximum numbers of plants and DM production were obtained when seed was drilled into cultivated seedbeds (Table l). Drilling rather than broadcasting seed into uncultivated plots increased plant numbers in all species. Harrowing after broadcasting increased yield in both cultivated and uncultivated treatments, but it improved plant number only in cultivated plots. The results clearly demonstrate the positive effect of some form of soil disturbance on establishment and subsequent productivity of sown species. Providing that there is adequate seed-soil contact for moisture exchange, direct drilling gives satisfactory establishment.

Table 1. Establishment and yield from different sowing methods

1. Carter E.D. (1987). In "Temperate Pastures : Their Production Use and Management" J.L. Wheeler, C.J. Pearson and G.E. Robards (eds.) Australian Wool Corporation/CSIRO pp. 35-51.

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