Influence of single applications of nitrogen on white clover nitrogen fixation in autumn and winter dairy pastures in south-west Victoria, Australia

  • FR McKenzie Department of Natural Resources and Environment, 78 Henna Street, Warrnambool, Victoria 3280, Australia
  • JL Jacobs
  • P Riffkin
  • G Kearney
Keywords: Australia, autumn, botany, dry matter yield, <i>Lolium perenne</i>, nitrogen, nitrogen fixation, pastures, perennial ryegrass, species composition, <i>Trifolium repens</i>, white clover, winter, yield, ammonia, fertilization, nitrate, pasture, phosphorus,


Abstract:Effects of nitrogen (N) (0, 15, 30, 45 and 60kg N ha-1) applied at five different times during autumn and early winter on the N fixation of Trifolium repens L. (white clover) in Lolium perenne L. (perennial ryegrass) white clover pastures were examined (Experiment 1). Effects of applying different N fertilisers (e.g. urea and ammonium nitrate) at 45kg N ha-1 in autumn, with and without phosphorus (P), potassium (K) and sulphur (S) on N fixation were also tested (Experiment 2). In Experiment 1, percentage N derived from the atmosphere (percent Ndfa) by white clover varied between 87% and 91% in the period after (24 to 36 days) N application. Increasing rates of N and time of application did not influence percent Ndfa. The amount of N fixed by white clover ranged from 0.8 to 3.7kg N ha-1 in the period after N application. Increasing rates of applied N produced a significant (P < 0.05) linear increase in the amount N fixed. In Experiment 2, percent Ndfa and amount of N fixed (1.9 to 4.1kg N ha-1) were unaffected by different N fertilisers, with and without P, K and S, in the period after (37 days) fertiliser application. For both experiments, fertiliser N increased dry matter yield while having no effect on white clover composition. It is concluded that single applications of N during the autumn and early winter benefit pasture growth without adversely affecting white clover N fixation or clover composition. This finding, however, will require further investigation.

Keywords: Australia; autumn; botany; dry matter yield; Lolium perenne; nitrogen; nitrogen fixation; pastures; perennial ryegrass; species composition; Trifolium repens; white clover; winter; yield; ammonia; fertilization; nitrate; pasture; phosphorus; potassium; ryegrass; victoria

African Journal of Range & Forage Science, Vol. 15(1 & 2), pp. 1–6

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eISSN: 1727-9380
print ISSN: 1022-0119