Barley nitrogen requirements: malt vs feed, rates and late N

Malt or feed: decide first

Barley nitrogen is a balancing act. Too little N cuts yield and protein. For malt barley, too much pushes protein over the top limit and the grain can be downgraded to feed.

• BCG (Victoria) gives the premium malt range as 9–12% protein, and says the challenge in good seasons is not going over 12%.
• A 1997 Queensland study cites malting standards of 8.5–12.0% protein, with large grain (85% retained on a 2.5 mm screen). Check the current receival standards for your variety before you set targets.
• DPIRD says around one third of WA barley is historically delivered as malting grade and the rest as feed, and malt receival depends on the variety being accredited and meeting quality specs at harvest.
• Feed barley has no protein ceiling, so N is managed for yield, much like wheat. See the nitrogen budget worked example.

How much nitrogen barley needs

The Queensland study (13 trials over four years) found barley used N efficiently until it reached about 90% of its maximum yield. Protein did not climb to levels unacceptable for malting until yield passed 85–90% of maximum. Its recommended method:

1. Soil test for nitrate-N to 1 m deep before sowing. The crop can use that nitrate if the soil is moist to 1 m.
2. Set a target of 90% of the expected maximum yield.
3. Allow about 17 kg of N taken up per tonne of grain.

Our arithmetic, as an example: a 5 t/ha potential gives a 4.5 t/ha target, and 4.5 × 17 is about 77 kg N/ha taken up by the crop. Subtract the soil nitrate-N to 1 m and the N you expect to be released from organic matter. The gap is what fertiliser has to supply, and the crop never recovers all of the fertiliser N you spread, so check the final rate with your agronomist. Urea is 46% N, so every 10 kg N/ha is about 22 kg/ha of urea. See how much urea per hectare for the conversion and our nitrogen calculator for cost.

High-yield crops: more N is not always more yield

In GRDC's Hyper Yielding Crops trials (2020), extra N above standard practice gave little or no extra barley yield but did raise protein. At Millicent (SA), adding 25% and 50% more N on top of 130 kg N/ha gave no extra yield even though protein was below 10%. The project concluded that on fertile soils, N is more likely to change protein than yield, and that high yields come from soil fertility built through rotations rather than fertiliser alone.

Late nitrogen to lift protein

If a malt crop looks like coming in under 9% protein, a late N application can lift it. In BCG's 2011 trial at Birchip:

• Urea applied at flowering raised protein but did not change yield, screenings, retention or test weight.
• As a rule of thumb, about 10 kg/ha of urea per tonne of expected yield raised protein by 1%. A 5 t/ha crop needed at least 50 kg/ha urea.
• One variety went from 8.6% to 9.7% protein with 50 kg/ha urea and made malt grade. Two others were already above 9% without extra N, so topdressing them only added cost.
• The first 50 kg/ha of urea lifted protein twice as much as the next 50 kg/ha.
• BCG says late N is easier to get right in barley than in wheat when you know starting soil N and moisture, because barley yield is more predictable.

Late N on the surface can be lost to the air if no rain follows; read how much N urea loses and protected urea vs urea. Liquid options are covered in urea vs UAN.

Signs barley is short of nitrogen

DPIRD (WA) calls nitrogen deficiency the most common nutrient deficiency in barley, especially in cold, wet conditions and on sandy soils in high rainfall areas. Plants are pale and stunted with thin stems. The oldest leaves yellow first from the tip down, turning almost white. Crops have fewer tillers and smaller heads, with low-protein grain. DPIRD recommends a whole-top plant test to confirm, and says a soil N test on its own is of little value for most WA soils. The wheat version of these symptoms is in nitrogen deficiency in wheat.

Product examples: Granular Urea, Summit Urea, UAN and Gran-Am where sulphur is also short. Compare urea and Gran-Am side by side or browse all nitrogen fertilisers. Always check with your agronomist before acting.