Opportunity to fix nitrogen when establishing crops

Preparation for drilling wheat and barley crops this autumn could include decisions about nitrogen efficiency – not just crop emergence and establishment.

With growers focused on using fertiliser more efficiently, modern endophyte seed treatment technology means plants can obtain some of their spring nitrogen from the air, says Syngenta field technical manager Jonathan Ronksley..

Crucial elements

“Factors such as cultivations, seed rate, drilling date and protecting against establishment diseases with a fungicide seed treatment remain crucial elements in establishment decisions,” says Dr Ronksley.

“But farmers are also looking to use nitrogen fertiliser more efficiently and farm more sustainably – and for the first time this autumn we have nitrogen-fixing endophyte seed treatment Nuello iN available for winter wheat and winter barley seed.”

Nuello iN contains two nitrogen-fixing bacteria – Pseudomonas siliginis and Curtobacterium salicaceae. These enter the plant via the developing root before colonising plant shoots and fixing atmospheric nitrogen.

Yield benefits

“They provide the plant with organic nitrogen and ammonium and are ‘always on’ throughout the whole season,” says Dr Ronksley. “This has the potential to supplement traditional fertiliser.”

Nuello iN seed treatment delivered a yield benefit equivalent to applying up to an extra 30 kg N/ha in four UK replicated field studies examining nitrogen fertiliser dose response curves in winter wheat last season, says Dr Ronksley.

This was echoed in 14 Adas split-field farm trials across the UK. Winter wheat treated with Nuello iN received a 30 kg/ha reduction in its standard nitrogen dose – but still maintained a similar yield to winter wheat receiving its full dose.

With yields averaging about 10.8t/ha, says this equated to Nuello iN giving a 3:1 return on investment. On light or shallow land sites, Dr Ronksley says using Nuello iN with a 30kg/ha nitrogen reduction gave an even bigger 5:1 return on investment.

Residual nitrogen

“This makes sense as these types of soils are often associated with lower availability of soil residual nitrogen,” explains Dr Ronksley.

Bigger average yield gains from Nuello iN were found on light or shallow land sites or second cereal sites in replicated trials where a standard 100% nitrogen dose was applied. Yield benefits were also found in hybrid winter feed barley.

“It’s always important to consult a FACTS qualified adviser for advice and guidance on nitrogen applications. But there are several scenarios where we see a role for Nuello iN as part of an integrated fertiliser strategy.

“These include winter feed wheat and winter feed barley where a decision has been made to reduce in-season synthetic nitrogen, and in winter wheat and winter barley where no reduction in synthetic nitrogen will take place but growers are looking to enhance yields.

Nutrient deficiency

Nuello iN may be particularly relevant on sites where soil nitrogen is limited. This could include light, shallow or nutrient-deficient soils; a second cereal position; or where nitrogen is applied late or in dry conditions.

“Farming is all about risk mitigation and this can help growers with that,” says Dr Ronksley. But it is not recommended to reduce nitrogen on milling wheat or malting barley, he adds.

“It is still important when using Nuello iN that it is co-applied with a suitable fungicide seed treatment, such as Vibrance Duo, to maintain protection against establishment diseases. Much of our trial work has been with Nuello iN co-applied with Vibrance Duo.”

In addition, Nuello iN has been observed to enhance early rooting, with an increase of 20% across three winter wheat and winter barley trials. Enhanced root development is associated with improved nutrient scavenging from the soil.