Pasture response to superphosphate application in topographically diverse landscapes of the Central Tablelands and Monaro regions of New South Wales

Phosphorus (P) as single superphosphate (9%P, 11%S) was applied annually at six rates ranging from 0-80 kg P/ha/yr for three years to north upper (NU), north lower (NL), south upper (SU) and south lower (SL) slope positions in three pasture paddocks i.e. 12 'locations', of the Central Tablelands (CT) and Monaro (M) region of NSW. The pastures used were based on native perennial grasses (Microlaena stipoides or Austrostipa spp. respectively for CT and M) or cocksfoot (Dactylis glomerata) (CT). A total herbage response to application of P was recorded at six out of 12 positions despite most locations having very low soil available P levels. Where an overall increase in production occurred it was linear and due to increased legume production at the native grass sites and to perennial grasses at the cocksfoot site. While responses were statistically significant, it may not be economically prudent to apply superphosphate to all responsive landscape positions. The results of this study indicate merit in adopting strategic fencing and differential fertiliser application strategies for improved economic outcome in topographically diverse landscape paddocks in NSW.