Sum16-36 Phosphorus rates in wheat, Northampton


To assess how wheat responds to phosphorus (P) fertiliser applications under different conditions, soil P stores and soil Phosphorus Buffering Index (PBI) across the wheat belt.

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Table 1: Soil Analysis
Fig 1: Yield
Fig 2: Yield Response Curve


  • There was a strong response to applied P under these conditions with a yield gain of 1.13 t/ha from 0 to 24 kg/ha P.
    According to nutrient recommendations, the value of P has been slightly underestimated at this site.
  • Yield was maximised at 4.7 t/ha with 24 kg/ha of applied P.
  • The highest returns were also generated from 24 kg/ha of P.
  • Despite the nutrient recommendation suggesting ~12 kg/ha P, high yields meant that this trial optimised yield and gross margin at 24 kg/ha.