SUM19-09: Nitrogen phosphorus and potassium boost for canola after soil amelioration, Merredin


To assess the combination of pre-drilled phosphorus and potassium rates and in-season nitrogen rates on ameliorated and non-ameliorated soils in the Merredin area.

Trial Details

Location: Nokanning Farms, Merredin.

Trial Size: 9 plots.

Soil Type: Sandy Loam.

Crop Sown: Canola, 15/05/2019, 82kg/ha.

Table 1: Pre-trial soil nutrient analysis.



Figure 1: Yield response of individual treatments clearly demonstrates the capacity of amelioration and, subsequently, adequate foundation P and K nutrition to enable increased efficiency of N utilisation.
Figure 2: The effect of nutrient application on the increased profit from canola on ameliorated soil in comparison to non-ameliorated soil.

Key Notes

  • Combinations of pre-drilled phosphorus and potassium and in-season nitrogen rates for canola were applied on deep-ripped and unripped soil areas near Merredin.
  • Low replication in design means results should are preliminary and should be applied with caution, but the trial demonstrated what is readily achievable in what were less-than ideal seasonal conditions for canola.
  • Ameliorated soil produced yield response to increasing rates of N, P and K applied, whereas non-ameliorated soil did not.
  • After addressing the biggest limiting factor – soil compaction – addition of P and K allowed in greater use efficiency of in-season N applications.
  • The additive effect of soil amelioration and increasing fertilizer supply was clearly expressed by additional margin returned from nutrient application to ameliorated soil.
  • Where ripping may improve profit by around $50/ha on it’s own, the addition of another 10 kg phosphorus, 20 kg potassium and 40 kg nitrogen per hectare to ripped soil suggested a profit lift of up to $140/ha.
  • It is important to support soil amelioration with appropriate nutrient range and rates in order to maximise profits from crop production.

Contact your local Area Manager Kobus Marais for more details on this trial, 0427 766 508.