Smarter nitrogen use in focus

12 Sep, 2017 12:00 PM
Best management practices need to be based on the best available information.

It's widely acknowledged that being smarter about the efficient use of nitrogen (N) opens doors to greater productivity, increased profit and reduced environmental impact, but what is the best way forward for particular farming systems?

This is the key focus of the national More Profit from Nitrogen Program (MPfN), a four-year partnership between Australia's four major intensive users of nitrogenous fertilisers: dairy, cotton, sugar and horticulture, led by the Cotton and Research Development Corporation (CRDC).

MPfN, supported by an injection of $5.8 million from the Australian Government's Department of Agriculture and Water Resources Rural R&D for Profit program, is in its first year of delivering findings from 10 research projects from a partnership of 23 organisations. Combined contributions have seen an unprecedented commitment of $15 million to nitrogen use efficiency (NUE) research.

"By bringing the four industries together, the result is definitely increased cross-sector collaboration to reduce duplication of effort and development of more progressive and expedited outcomes for the investment than research undertaken in isolation," science co-ordinator for the program Marguerite White said.

"With 70 PhD, post-doctorate, research and technician positions contributing time on this from some of Australia's leading research organisations, plus the incredible contribution from all the industry farm extension programs, MPfN will deliver highly advanced outcomes that will be game changers rather than incidental steps for NUE."

MPfN is working towards making a marked difference to farm profitability, while reducing environmental impacts, by reducing the amount of N required to produce a unit of product.

Any producer knows that there are many contributing factors when deciding on how, when and where to use N ù too little at the wrong time may reduce yield potential, while too much when not necessarily needed can greatly impact on profitability. It can be a balancing act.

MPfN has been designed to engage with farmers from the beginning to ensure it delivers outcomes from research that will provide practical solutions. More than 31 study sites, established along the eastern seaboard, from Darwin to Hobart, will also be used to demonstrate and host local field days to encourage local input. These sites are further supported by laboratory analysis, experiments, simulation and modelling.

Program research is being undertaken under three focus areas for improving productivity and profitability through N use. These are:

Greater knowledge and understanding of the interplay of soil, weather, climatic and farm management factors to optimise N formulation, rate and timing in relation to irrigation practices.

Greater knowledge and understanding of the contribution (quantifying rate and timing) of N mineralisation to a crop or pasture's nitrogen budget.

Greater knowledge and understanding of how enhanced efficiency fertiliser (EEF) formulations can better match a crop or pasture's specific N requirements by developing new ones and optimising existing ones.

Dairy projects

Dairy Australia has supported three projects under the MPfN Program, each contributing to one or more of the focus areas.

The University of Melbourne's project, Improving Dairy Farm Nitrogen Efficiency Using Advanced Technologies, is seeking to gain a better understanding of the amount of N supplied through mineralisation to dairy pastures under both irrigated and non-irrigated conditions in South West Victoria, with the trial site established at Allansford, near Warrnambool.

Project leader Dr Helen Suter said: "The outcome for farmers and their advisers will be a tool that can provide a more reliable estimate of mineralised available N under different seasonal conditions so that N fertiliser inputs can be adjusted accordingly. Simply, it is about precision application ù so less wastage and less input costs".

Recently the project conducted a workshop with local farmers to seek input into the concept of the mineralisation calculator tool and will hold similar events for the lifespan of the research.

So far trial research, undertaken across the 2016/17 summer and 2017 autumn, is resulting in practical information for farmers. For example, findings demonstrate that the process of mineralisation results in a build-up of N in the pasture rooting zone over summer on the dryland site, providing ample available N for pasture growth once sufficient rain falls in autumn and would suggest that an application of N at the general guidance rate of 40- 50 kilograms of nitrogen per hectare may not be warranted at this time of year. Harvest results support this with plots fertilised with N showing little yield response.

Queensland University of Technology's (QUT) project, Increasing Nitrogen Use Efficiency in Dairy Pasture, is a partnership with the NSW Department of Primary Industry. Two core study sites have been established at Casino, in the subtropical Northern Rivers region of NSW, and Camden, west of Sydney.

With research components in all of the MPfN Program focus areas, the project is investigating the interactions between nitrogen, mineralisation and applied water to establish precision irrigation recommendations to optimise NUE while increasing water use efficiency.

The project is also trialling a number of EEFs to ascertain optimal application timing and rates based upon prevailing and predicted climatic conditions.

"The important measurement for farmers is the agronomic efficiency which will be ascertained," QUT's project leader Dr David Rowling said. "That is, how will the results reflect increased quantity and quality feed from less nitrogen and water input.

"The trial sites provide a testbed for current best management practices where we can measure nitrogen loss pathways under a suite of different nitrogen, irrigation and EEF management practices, across seasons. If we better understand the losses and key processes, such as mineralisation, which contribute to the available N for plant growth, we can more accurately recommend fertiliser formulations, rates and timing for the NSW and subtropical dairy systems."

Under a partnership between the University of Melbourne (UoM) and the Tasmanian Institute of Agriculture (TIA), Quantifying the Whole Farm Systems Impact of Nitrogen Best Practice on Dairy Farms is testing and refining current best management recommendations. The team is using farm systems analysis and modelling to review current N fertiliser best management practices and 'rules of thumb' recommendations under different farming systems, soils and climate scenarios in five dairy regions of Australia.

The work to date has shown that pasture response rates (kg dry matter/kg N fertiliser) and N loss pathways to the environment (i.e. leaching, volatilisation and denitrification) are dependent on current soil and water conditions, farming system and short-term weather patterns.

At all sites, the Fert$mart recommendation of application rates between 20 and 50 kg N/ha per grazing rotation were re-affirmed as being the most efficient in terms of both pasture growth and minimising N losses. However, the optimum rates varied according to season and location, with the value of autumn N being highly dependent on the previous summer rainfall, while summer N responses were obviously dependent on rainfall in the regrowth period. By using modelling, the project aims to increase the capability of farmers and their advisers to use predictive methods to increase productivity, profitability and environmental stewardship.

Project leader Prof. Richard Eckard said: "Best management practices need to be based on the best available information. So we are going back to basics and putting each and every recommendation through thorough testing under a comprehensive range of scenarios. Modelling is a key tool for us to achieve this".

The team are working closely with farmers and farm consultants to ensure that the modelling of study farms is as realistic as possible.

"Using modelling we can upscale the experimental work and refine understanding to the farm scale," Prof Eckard said.

"This is an important step as nitrogen management decisions at the farm level need to consider weather and soil conditions, but are ultimately made based on farm feed supply, animal demands, the price and availability of other alternative feeds.

"Using farming systems modelling we can investigate various combinations of these issues. It is hoped that the final result will be more efficient, productive and profitable dairy farming systems."

The results of all three MPfN research projects will be integrated into industry programs such as Dairy Australia's Fert$mart Program and will contribute to the ongoing efforts of industry to increase home-grown forage consumption with improved water, cost and greenhouse gas emissions efficiencies.

Taking Australia's dairy industry to a broader audience, this leading work will also be showcased to national and international audiences through science journals and conferences.

Marguerite White said: "With research and demonstration underway in most dairy regions, farmers are encouraged to become involved in local project trials as practical relevance to farm management and assessing accurate profitability gains for the farm business is paramount to the ongoing legacy of the More Profit from Nitrogen Program."D

More can be found on the dairy projects by visiting the MPfN Program webpage and clicking through to the dairy site.

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