Sum18-05 N x P in Barley, Sth Burracoppin


To assess the response of wheat to nitrogen (N) and phosphorus (P), whilst examining the longevity effect of soil amelioration activities, deep ripping and liming.

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Table 1: Soil Analysis
Figure 1: Yield and Protein Responses to Nitrogen and Phosphorus

Figure 2: Responses to Nitrogen and Phosphorus


  • Acidic subsoil constraints limited root exploration, plant growth and harvest yield.
  • There was a strong in-season biomass and yield response to applied N.
    Despite the low P status of the site, there was a weak response to applied P.
  • The high fertilizer treatment (120 kg N/ha & 24 kg P/ha), had the highest in-season plant growth and harvest yield, but did not maximise gross margins.
  • Yield ranged between 0.6-2t/ha and was low considering the favourable rainfall conditions.
  • Profits were not reflective of the higher grain prices, due to poor grain quality and yield.
  • The most profitable treatment of $440/ha was 120 kg N/ha and 18 kg P/ha, which also optimised yield.