SUM19-13: N Rates, N-Calc Recommendations & Cereal Varieties, Morawa Agricultural College Site


To assess the response of Barley, Oat & Wheat varieties to applied nitrogen (N) fertilizer. To test and calibrate the extension of nitrogen-rich strips(N-gauges), Normalised Difference Vegetation Index (NDVI) measurement and the In-Season Nitrogen Calculator (N-Calc) to assist in mid-season nitrogen decisions and maximise nitrogen efficiency and returns.

Trial Details

Location: Morawa Ag School

Trial Size: 35 treatments x 3 reps = 105 plots.

Soil Type: Sandy loam

Crop Sown 1: Rosalind (feed) & Spartacus (malt) barley, sown on 07/05/2019 at 75 kg/ha.

Crop Sown 2: Devil (AH), Havoc (AH), Scepter (AH) & Vixen (AH) wheat, sown on 07/05/2019 at 100 kg/ha.

Crop Sown 3: Pallinup (Oat), sown on 07/05/2019 at 85 kg/ha.

Table 1: Pre-trial soil nutrient analysis


Figure 1: Wheat yield and protein increases with quantity of N applied. Devil yielded lower than Vixen but Havoc had the highest protein content. Due to harvest issues, Vixen is an average of Rep 1 & 2 only.
Figure 2: Barley yield and protein increases with quantity of N applied. Spartacus yielded higher than Rosalind, but they had similar protein contents.
Figure 3: Oat yield decreased with applied N. Protein (not including rep 1) increased with higher N rates.
Figure 4. a) Cereal response curves showing no trend in yield response to increasing N rates in any of the cereals. Wheat is slightly more responsive than barley or oats. b) Gross margins curves show returns decreasing with applied N. Barley is more profitable than wheat or oats.

Key Messages

  • Morawa experienced a decile 3 growing season in 2019 with significant dry periods during [1] early April to mid-June, [2] most of July and [3] all September. Rainfall pattern affected the yield potential in this trial.
  • The N-Calc underestimated yield and the N rate needed to reach 10.5% and 11.5% grain protein, this is most likely due to the below average rainfall experienced in this area.
  • There was a strong biomass response to increasing N rates, but the extended dry period at the end of the season (August – October), meant the biomass did not follow through to yield.
  • Barley had the highest average yield of 450kg/ha, then wheat with 379kg/ha and oats with 69kg/ha.
  • Applying 10kg N/ha upfront maximised both yield and gross margin returns across all varieties.

For further information about this trial get in touch with local Area Manager Juliet McDonald, 0429 945 332.