Chasing Protein: Is Late Nitrogen Worth It?

Analysis of grain data shows that in many years, 50–90% of wheat in the Facey catchment is downgraded from APW1 due to low protein.

Protein is mostly driven by nitrogen availability and seasonal conditions. High yields from good rains often dilute protein, while poor finishes can lift it.

Applying nitrogen late (booting stage) is one of the biggest levers farmers have to influence grain quality. However, because it doesn’t impact yield, the big question is whether it’s a worthwhile investment.

What Drives Growers’ Nitrogen Decisions?

A recent survey with growers in the Facey Group catchment highlighted how farmers in the Wheatbelt are currently managing nitrogen and what drives their decisions.

Results showed:

  • Seasonal conditions determine whether a third ‘top-up’ is applied.
  • Legumes in the rotation lead some (but not all) farmers to reduce N rates — showing inconsistent management.
  • Soil type only influences decisions for some growers, suggesting room to better match N to yield potential.
  • Protein is not a driver of nitrogen decisions.

How Do the Economics Stack Up?

Simply put, the economics of chasing protein are marginal:

  • Raising protein by 1% in a 5 t/ha wheat crop requires around 50 kg N/ha.
  • At mid urea prices, this costs about $16.50/t grain.
  • Protein premiums have historically averaged only $13/t.

Late N applications may pay in rare cases — for example, when premiums are unusually high or grain protein sits just below a cut-off threshold (e.g. 0.5%). But predicting protein outcomes at that level of accuracy is a challenge.

For other crops, the case is even weaker:

  • Barley usually meets malt protein targets without late N.
  • Canola oil content is rarely an issue, so late N has little value.

Take-Home Messages

  • Most growers are on the right track: fertilising for yield, not chasing high protein.
  • Protein premiums are usually too low to justify late N applications, unless better prediction tools become available.
  • Legumes are underused but valuable, helping add nitrogen and stabilise protein.

🌱 This baseline nitrogen analysis was undertaken as part of the GRDC RiskWi$e project, in collaboration with Facey Group.

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