Greenhouse gases and farming by Brendon Cant

VIGOROUS and informed debate must start soon in Australia's graingrowing community if significant climate change issues are to be tackled intelligently and while there is still enough time to make a meaningful impact.

About 30 stakeholders, including growers and scientists, met in Perth in August to thrash out what they knew about greenhouse, how they proposed to reduce greenhouse gas emissions and what would be their priority action areas.

Warwick Jones, Project Manager with Agriculture Fisheries and Forestry Australia's (AFFA) Greenhouse Group, said the workshops, held around Australia, revealed how little most growers knew about how greenhouse was already affecting their farming operations.

Cuballing grower Darrel Dent, who attended the Perth workshop with fellow GRDC Western Regional Panel members Juliann Lloyd-Smith and Chairman Dale Baker, said he was amazed to learn that one-quarter of emissions from agriculture come from nitrous oxide through soil disturbance, residue burning and losses from nitrogen fertilisers.

Nitrous oxide flows within cropping and grazing systems are not well understood. Unlike carbon, nitrous oxide releases from the soil are influenced dramatically by temperature and moisture, with soil types within a paddock also having an impact.

There are three key reasons why nitrous oxide is a major issue for the grains industry.

  • Because nitrous oxide is such a potent greenhouse gas, small emissions require a very large effort in carbon sequestration to offset it. Work in the USA suggests that for every kilogram of nitrous oxide produced, 140 kg of carbon needs to be taken from the atmosphere and sequestered into the soil.
  • The advent of continuous cropping has lifted the use of nitrogenous fertilisers.
  • Nitrous oxide released to the atmosphere is a waste of a costly resource.

One farmer's audit

Darlington Point, NSW, farmer David Cattanach is the first farmer to join the greenhouse challenge and complete a paper audit of greenhouse emissions on his property. He told the Perth workshop that nitrous oxide from nitrogenous fertilisers was his big emission source (42 per cent as carbon dioxide equivalents), followed by diesel fuel (35 per cent), soil disturbance (7 per cent), domestic electricity (7 per cent), crop burning (5 per cent), LPG (2 per cent) and other (2 per cent).

The Kyoto protocol required a timeframe for government to develop and implement abatement strategies by 2008- 2012, with emissions to be 108 per cent of 1990 levels.

Research into nitrous oxide production could give a win-win solution. For example, a better understanding of how nitrogen fertilisers break down in the soil after being applied could lead to less nitrogen being applied and better timing of applications.

Contact: Mr Warwick Jones, AFFA 026272 5311