Tactical challenge for in-season nitrogen application

Professor Chengdao Li inspects barley at a field trial of the genetic, environmental and management factors that reduce head loss. Photograph by GRDC.

Professor Chengdao Li inspects barley at a field trial of the genetic, environmental and management factors that reduce head loss. Photograph by GRDC.

HOW much nitrogen should be applied in-season?

That is the burning question many WA grain growers are currently contemplating following recent rains which have triggered a revision of the outlook for yields.

After the late start to the season, rainfall in many parts of the State in June has spurred growers into activating growing season nitrogen (N) application programs in a bid to capture water-limited yield potential.

Grains Research and Development Corporation (GRDC) manager of agronomy, soils and farming systems - west, Rowan Maddern, said growers needed to consider a number of factors in their fertiliser decision making in an effort to match a crop's N requirements.

"Knowing the status of existing nutrient levels and any change in yield potential is important in determining how much nitrogen should be applied," Dr Maddern said.

"It's a balancing act - growers don't want to miss out on capturing yield potential but they also don't want to be spending money on inputs if a return on that investment is not likely."

Dr Maddern said growers should consult with their advisers about any review of their nutrient programs, and recommends plant tissue testing as a useful in-season tool to refine initial recommendations.

The GRDC also has available to WA growers a suite of Western GrowNotes publications for all crop types which offer information on in-season application of N.

These publications are available at https://grdc.com.au/grownotes.

The Western Wheat GrowNotes includes a 'best-bet nitrogen strategy' and a decision tree for in-season N applications according to the progress of the season and crop developmental stage.

Meanwhile, the GRDC has recognised that the impact of incorrect N applications results in several issues for WA wheat growers, primarily relating to grain quality.

Dr Maddern said growers were asking how they can capitalise on good seasons in time to make more profitable nitrogen decisions, thereby making optimum nitrogen applications for protein and best economic response while maintaining or increasing yield.

"Growers at GRDC Western Regional Cropping Solutions Network (RCSN) open forums in 2018 highlighted that they lack the tools and knowledge to make profitable in-season decisions, which they consider to be a constraint to their profitability," he said.

"To address this issue, the GRDC is investing in a new western project, 'Tools for growers that can enable best practice in-season nitrogen management to optimise economic returns and grain protein'."

Running until early 2021, the project's outputs will include nutrition master classes in the Esperance, Kwinana East and Kwinana West port zones, providing growers with a summary of N cycling and availability within a cropping season and enhancing their understanding of the basic requirements to improve cost-effective fertiliser decisions and ultimately grower profitability.

Other outputs from this new investment include new resources for growers and consultants to aid in N decision making to optimise economic returns.