Fiona Tomney1, Brian Dzoma2, Ross Ballard3 and Nigel Wilhelm3
1SARDI, Minnipa Agricultural Centre, 226 McKenzie Rd, Minnipa SA 5654 email@example.com
2SARDI, Loxton Research Centre, Loxton SA 5333
3SARDI, Waite Research Precinct, Urrbrae SA 5064
Following grower reports of low soil nitrogen (N) following vigorous medic-based pastures on the upper Eyre Peninsula of South Australia, management practices including herbicides and fertilisers were investigated for their effect on the N fixation of strand medic pastures at six field sites on the upper Eyre Peninsula. Applying phosphorus to soils with low P reserves at medic pasture establishment increased medic shoot dry matter and improved N fixation. The addition of urea at seeding reduced N fixation by the medics at some sites. Soil residues of the herbicide Logran reduced medic growth at one site. The application of a full label rate of Agritone 750 Herbicide (applied late when the medic plants were 5-7 cm in diameter) decreased pasture production and N fixation.