How to manage nitrogen rates in high-yielding malting varieties

Spring malting barley growers can increase nitrogen fertiliser rates when using modern varieties to lift yields and still meet the needs of maltsters.

New varieties such as Planet, Irina and Laureate allow growers to target yields of 8t/ha, while key grain nitrogen levels are kept low to meet malting industry standards compared with older varieties such as Propino.

Edward Downing, national crop nutrition technical manager at agronomy group Frontier, says this will give growers the chance to push yields and profit levels higher.

“Modern varieties have been bred for high yields while still maintaining low grain nitrogen levels for the maltsters,” he says.

The British spring barley area is set to rise 17% this season due largely to the fall in winter oilseed rape plantings, with most of the barley increase likely to be in central England, from Lincolnshire through to Warwickshire.

See also: Hampshire malting barley growers push up yields

Nitrogen targets

The spring malting barley market for brewing targets grain nitrogen of below 1.85% and is dominated by varieties Propino, Planet and Irina, whereas the distillers look for grain below 1.65% nitrogen and the top variety is Concerto, with Laureate seen as meeting both markets.

Mr Downing says trials have shown that increasing nitrogen rates from 125kg/ha to 175kg/ha resulted only in a 0.1% rise in grain nitrogen, and all grain came well within brewing malting standards.

Some growers are already using levels of 160-170kg/ha of nitrogen to achieve high yields, but the 10-year average for the nationwide spring barley crop is just 104kg/ha.

“Maybe this gives growers the chance to chase more yield, as nitrogen is needed to build yield,” he adds.

Towards high yields

Spring barley growers should be looking at the history of their nitrogen use and final grain nitrogen to assess whether they are putting on enough fertiliser as they aim for crops of more than 800 ears/sq m to give a yield of 8t/ha, according to Mr Downing.

Furthermore, he advises growers to divide their nitrogen applications, suggesting either a two-way or three-way split.

The two-way split should be in the seed-bed and at the three-leaf stage (GS13), while the three-way split also includes an application at the start of stem extension (GS30-GS32).

“Those who put all the nitrogen on in the seed-bed should try a two-way split. While those using a two-way split could try a three-way split,” he says.

In a trial using 130kg/ha of nitrogen, putting all the nitrogen on the seed-bed in one application yielded 6.96t/ha, while increasing the applications to a 50:50 two-way split yielded 7.26t/ha.

A three-way split of 30% in the seed-bed, 50% at the three-leaf stage and 20% at GS30-32 gave the highest yield of 7.47t/ha, while the grain nitrogen for all three trial plots was largely similar at 1.5%.

Seed-bed phosphate

In addition to nitrogen, phosphate is key in the seed-bed, along with potash, as phosphate plays a huge role in encouraging rooting and rapid development, says Mr Downing.

“Nearly all spring crops will benefit from fresh phosphate, irrespective of how much phosphate is in the soils,“ he adds.

His trial work shows using 65kg/ha of phosphate gave a yield boost of 0.65t/ha, worth nearly £60/ha, even with a soil phosphate index at a high 3.6 level.

Furthermore, sulphur is important as it can improve malting quality and loaf quality for milling wheats, and he recommends 25-50kg/ha for spring barley and 40-50kg/ha for spring wheat.

Mr Downing was speaking to Farmers Weekly after giving a presentation to a Frontier regional growers briefing.

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