Field Research & Agronomy

Nitrogen and phosphorus with and without potassium in oats

AIM:

‍Part of a continuing trial series to evaluate the response of cereals to nitrogen (N), phosphorus (P) and potassium (K) fertilizer under different soil characteristics and rainfall levels over the state.
Additionally, helping to further improve the guidance and advice given to local farmers when making fertilizer decisions.

For further details contact your local Area Manager or the Summit Research Team

CONCLUSIONS

• Yields were poor across the trial due to low rainfall at the start of the growing season.
  1.02t/ha was the greatest tonnage achieved from applying the highest fertilizer rate (N60, P18 & K20).
• Response curves indicated that yields had not been maximised by P18, but yield was seen to plateau at N20.
  A yield increase of 29% was achieved from applying N60 and 42% from P18.
• Soil test results suggested adequate levels of P (37.5mg/kg Colwel P, 0-10cm) yet there was a significant yield response to applied P.
  Soil K (86mg/kg Colwell K, (0-10cm) status was also sufficient and a yield response was noted, but was not significant
• Gross margin calculations demonstrated poor returns with the greatest profit being $102/ha from applying nil fertilizer.
• Due to lack of early and mid-season rainfall, top-up N application timing was not ideal to gauge the full N response effect and contributed to decreased gross margins.