SUM20.GP1: GRDC NPK Projects - P Rates in Scepter Wheat, Moorine Rock


This trial is part of a series of trials contributing to GRDC Project UWA1801-002RTX looking at ‘profit from N, P and K fertilizer inputs into the evolving cropping sequences in the Western Region.

Trial Details

Location: Moorine Rock

Trial Size: 2.2m x 10m, 8 treatments x 4 reps = 32 plots

Soil Type: Sandy Clay Loam.

Crop Sown: Scepter Wheat, sown 2/05/2020 at 78kg/ha

Season Rainfall: 162 mm, Moorine Rock DPIRDstation, 66 mm below long-term average.

Table 1: Pre-trial soil nutrient analysis


Figure 1: Individual treatment yield (bars) and protein (lines) presented as the mean across 4 replicates. There is a significantincrease in yield with applied P.

Figure 2: a) Individual gross margins showing profits increasing as the rate of P applied increased. All treatments were graded ASW1. b) Return additional to average gross margin returns from control (nil P). Data shows the addition of 40kg P/ha increased profits by 80%.

Key Messages

  • Plant growth significantly increased with phosphorus rates.
  • Yield was maximised at 40kg P/ha, ranging between 1.36t/ha and 4.04t/ha.
  • The most profitable treatment was $1100/ha when 40kg P/ha was applied.
  • Applying a low analysis product as an alternative source of P to MAP had no significant effect on emergence, in-season biomass or yield.

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