Research update: nitrification inhibitors

Research update: nitrification inhibitors

The following update covers one of the three PICCC projects funded through the national Nitrous Oxide Research Program. For more information, visit the project's webpage.

The potential of inhibitors for the mitigation of nitrous oxide emissions from animal production systems in south-eastern Australia

Project team: Kevin Kelly (DPI), Graeme Ward (DPI), Sally Officer (DPI), James Hollier (DPI), Richard Eckard (PICCC) and Tim Huggins (UM)

By Kevin Kelly, August 2011

Background   Animal production is a significant contributor to nitrous oxide (N₂O) emissions, with about 27% of the N₂O emitted from agricultural soils stemming from direct emissions from animal production. The principal source of this N₂O is urine and manure excreted onto pasture and rangelands.
Research in New Zealand has shown that the nitrification inhibitor dicyandiamide (DCD) can reduce N₂O emissions when surface-applied to pastures. To assess the potential of DCD as a mitigation tool, a team of PICCC researchers is looking at the impact of strategic DCD applications in animal production systems in south eastern Australia.

Research outline   Since commencing work in May 2009 the project team have completed three experiments, each of which has examined:

  1. N₂O emissions from urine patches. A range of timings of both urine and DCD application were tested, and emissions were measured using an automatic enclosure chamber system linked to a Fourier Transformed Infrared spectrometer. This component is based at DemoDAIRY in south western Victoria.
  2. The impact of the same application treatments on pasture production. Pasture dry matter was measured on six sites across the dairying region in south western Victoria.

Experiments have focused on the application of DCD (10 kg a.i. / ha, solubilised in water) either in autumn or late winter with dairy cow urine applied at a patch rate (approximately 1000 kg N / ha) deposited either immediately prior to DCD application or up to three months afterwards.

Results To date the team have found:

  • when DCD was applied in August 2009 and urine applied in either August or September 2009, N₂O emissions were reduced by about 35% (measurement period 240 days);
  • when DCD was applied in late April 2010 and urine applied in either late April or May 2010 N₂O emissions were reduced by about 45% (measurement period 155 days);
  • when DCD was applied in mid September 2010 and urine applied to 25% of the chamber area in September, October, November and December 2010, N₂O emissions were reduced by about 36%, and when DCD was applied after each urine application N₂O emissions were reduced by about 73% (measurement period 225 days).

Experiments assessing the impact of DCD on pasture production have had the same treatments applied except that ‘synthetic’ cow urine has been used. Results have shown statistically significant responses to DCD at some sites at the whole-of-urine-patch level, however when scaled up to paddock level they are likely to be negligible.

Implications   With demonstrated reductions in emissions of at least 35%, the use of DCD has considerable potential for integration into an emission reduction strategy under the Carbon Farming Initiative.

The research team will commenced another experiment in early May 2011 using the same treatments as those used in September 2010. The final experiment will commence in October 2011, before the project's scheduled finish in June 2012.

 

This project is supported by funding from the DPI, the Australian Government Department of Agriculture, Fisheries and Forestry under its Australia's Farming Future Climate Change Research Program, and Dairy Australia, with the external contract managed by the Grains Research and Development Corporation.