NITROGEN use was the major topic of discussion at the seventh annual Northern Australia Crop Research Alliance (NACRA) field day near Kununurra on July 21.
This event was supported by the Grains Research and Development Corporation's (GRDC) Northern Agronomy Project, which is into its fourth year.
The field day was a targeted and interactive farmer and researcher focused event with the emphasis on delivering the most relevant industry driven research directly to the growers.
More than 30 guests, representing the entire Ord farming community, were in attendance.
NACRA secured professor Mike Bell from the University of Queensland who is one of the leading authorities on applied soil science - and in particular crop nutrition in irrigated agriculture.
He specialises in soil fertility management and sustainable management systems in grains, cotton and sugarcane and heads the national GRDC project to reduce offsite nitrogen losses and improve nitrogen use efficiency in the grains industry.
Professor Bell also has a strong focus on balancing the environmental impacts of agriculture with the imperatives for productivity and profit, through his work with initiatives to improve water quality in the Great Barrier Reef lagoon and minimise greenhouse gas emissions from cropping industries.
He gave a comprehensive presentation on nitrogen as a crop input in maize.
This was in context of the escalating costs of fertiliser inputs such as urea and DAP over the past 18 months.
Topics discussed included overall interactions of nitrogen with water and soil, conversion from fertiliser product into plant usable forms of nitrogen, pathways for its losses, how nitrogen is obtainable from crop residue breakdown and the importance of soil testing to guiding fertiliser decisions.
Other speakers included local research agronomists Jack Daniel and Jodie Pengel from NACRA.
Also represented on the day were GRDC, University of Queensland, Department of Primary Industries and Regional Development (DPIRD) and NT Farmers.
Topics discussed included overall interactions of nitrogen with water and soil, conversion from fertiliser product into plant usable forms of nitrogen, pathways for its losses, how nitrogen is obtainable from crop residue breakdown and the importance of soil testing to guiding fertiliser decisions.
NACRA agronomist Jack Daniel gave this a local context, highlighting diminishing returns of high nitrogen (N) inputs last season in addition to what the 2021 crop had supplied to the 2022 'N bank'.
The importance of considering nitrogen inputs as a multi-year strategy was highlighted with the discussion of the 'N Bank', which will usually provide more nutrients to the subsequent crop than in season fertiliser application that year.
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Similar to yield responses, this also has diminishing returns at higher rates, highlighting more is not better.
NACRA is also collecting a comprehensive commercial data set to complement replicated trial sites.
Chickpea nodulation and its interaction with soil nitrogen was another topic of discussion.
Previous NACRA findings suggested residual nitrogen from the previous crop, usually maize, may inhibit chickpea nodulation.
However, this nitrogen is also usable to the following chickpea and can be in levels to support a high yielding crop in the absence of nitrogen and/or nodulation.
To determine the source of nitrogen at this trial site samples will be sent to a specialist NSW laboratory facility which can differentiate atmospheric N fixed through nodulation and soil N.
This test required plots of canola to be planted in each plot, with canola not being able to fix atmospheric nitrogen.
This turned a few heads, with the traditional Wheatbelt crop being a long way from its usual home in Kununurra.
The final presentation was delivered by NACRA agronomist Jodie Pengel who highlighted new large-seeded Kabuli chickpea genetics.
These new lines were crossed at the University of Sydney's Narrabri research facility as part of the recently completed Co-operative Research Centres Projects in 2019.
These have been grown in Kununurra since 2020 and display seed sizes larger than the largest commercial industry standard, with an improved plant habit demonstrating improved yields.
The best current commercial chickpea variety offerings were also highlighted, in the GRDC supported National Variety Trial (NVT), which has been conducted in Kununurra since 2017.
