SUM20.13: Factorial Nitrogen x Phosphorus rates to support Spartacus Barley Production, Mukinbudin


Assessing standard crop fertiliser practice against new strategies. This trial assesses the response of barley under a factorial nitrogen (N) and phosphorus (P) fertilizer application trial design in the Mukinbudin area to increase recognition of the value of optimal N and P to barley yield, grain quality and profitable returns.

Trial Details

Location: Mukinbudin.

Trial Size: 2.2m x 10m, 16 treatments x 4 reps = 64 plots.

Soil Type: Clay loam.

Crop Sown: Spartacus Barley, sown 24/04/2020 at 77kg/ha.

Season Rainfall: 119 mm, BOM Wattoning, 72 mm below long-term average.

Table 1: Pre-trial soil nutrient analysis.


Figure 1: Harvest yield (bars) and grain protein (lines) acrossfour replicates. Yield increased with applied P.

Figure 2: All yield response curves to P and N rate applications. There was a strong response to P and a weak response to N. Mitscherlich function is fitted to each dataset.

Figure 3: Grouped mean gross margins for applied N and P. Returns decreased with increasing rates of N and increased with increasing rates of P.

Key Messages

  • Plant growth significantly increased with both applied N and P.
  • Yield insignificantly increased with increasing rates of P, ranging between 1.00t/ha and 1.52t/ha.
  • The most profitable treatment was 18kg P/ha and 25kg N/ha, returning $275/ha.
  • The trial data demonstrated the value of establishment P, even under the low rainfall season conditions.

For further information about this trial please get in touch with local Area Manager Kobus Marais