Syngenta: Endophyte bacteria seed treatment brings N fixing opportunity to crop establishment decisions

Decisions taken in readiness for planting this autumn’s wheat and barley crops should be about more than simply aiding crop emergence and establishment, says Syngenta field technical manager, Dr Jonathan Ronksley.

With growers focused on using fertiliser more efficiently, he says modern endophyte seed treatment technology also makes it possible for plants to obtain some of their spring nitrogen (N) needs fixed from the air.

″Clearly, 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. ″However, farmers are also looking to use N fertiliser more efficiently and farm more sustainably, and for the first time this autumn we have available the N-fixing endophyte seed treatment, Nuello^® iN, for winter wheat and winter barley seed.

″Containing two strong N-fixing bacteria – Pseudomonas siliginis and Curtobacterium salicaceae – these enter the plant via the developing root, before colonising plant shoots and fixing atmospheric N. They provide the plant with organic N and ammonium and are ‘always on’ for the duration of the season. This has the potential to supplement traditional fertiliser applications.″

Pointing to results from four UK replicated field studies examining N fertiliser dose response curves in winter wheat last season, Dr Ronksley says Nuello iN seed treatment was found to deliver a yield benefit equivalent to applying up to an extra 30 kg N/ha on average.

This was echoed in 14 ADAS split-field farm trials across the UK, he says, where winter wheat treated with Nuello iN which received a 30 kg/ha reduction in its standard N dose maintained a similar yield to winter wheat receiving its full N dose. With yields averaging 10.80 and 10.83 t/ha respectively, Dr Ronksley says this equated to Nuello iN giving a 3:1 return on investment. On light or shallow land sites, he says use of Nuello iN with a 30 kg/ha N reduction gave an even bigger 5:1 return on investment.

″This makes sense as these types of soils are often associated with lower availability of soil residual N,″ explains Dr Ronksley. ″Indeed, across both small plot replicated and split-field trials where a standard 100% N dose was applied, we also found bigger average yield gains from Nuello iN on light or shallow land sites or second cereal sites. We’ve also seen a yield benefit from Nuello iN in hybrid winter feed barley.

″Clearly, it’s always important to consult a FACTS qualified adviser for advice and guidance on N applications. However, there are several scenarios where we see a role for considering 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 N inputs, and in winter wheat and winter barley where no reduction in synthetic N will take place but growers are looking to enhance yields.

″In the latter scenario, Nuello iN may be particularly relevant on sites where access to soil N is often limited – for example light, shallow, or nutrient-deficient soils; or in a second cereal position; or due to other factors such as late N application, soil N lock-up, or dry conditions. Farming is all about risk mitigation and this can help growers with that. Currently it is not recommended to reduce N on milling wheat or malting barley.

″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, Dr Ronksley says Nuello iN has been observed to enhance early rooting, with an increase of 20% across three winter wheat and winter barley trials. He says enhanced root development is associated with improved nutrient scavenging from the soil.