By David Fogarty, Climate Change Correspondent, Asia

SINGAPORE, March 26 (Reuters) - Farmers of the future will have to use cattle and sheep that belch less methane, crops that emit far less planet-warming nitrous oxide and become experts in reporting their greenhouse gas emissions to the government.

Agriculture is a major source of greenhouse gases and globally that share will rise as demand for food from growing human populations also increases, scientist Richard John Eckard of the University of Melbourne said on Thursday.

But farmers are facing a near-impossible challenge: feeding the world while trying to trim emissions and adapt to greater extremes of droughts and floods because of global warming, he said.

In coming years, farmers will have to monitor and report emissions as more nations move towards emissions trading.

"We want agriculture to feed the world. We want farmers to be viable and continue to increase the rate of productivity growth. At the same time, we're telling them they are going to face a more harsh climate they need to adapt to.

"On top of that you impose a policy that you can now only emit a fraction of the emissions that you were emitting," he told Reuters from Perth, Western Australia, during a climate change conference.

Eckard said research into ways of trimming those emissions while maintaining production growth was not advanced enough.

Australia, a major beef, dairy, wheat and wool producer, is aiming to launch the world's most sweeping emissions trading scheme from mid-2010.

Emissions from agriculture will be exempt until at least 2015 in part because technology to curb farm emissions is still in its infancy but also because adding costs to farmers is unpopular.

But the government has said it is determined to tackle emissions from agriculture one way or another because they comprise 16 percent the nation's total. In New Zealand, about half of national emissions come from agriculture.

CLEVER CATTLE, SMART CROPS

Methane, which is about 20 times more powerful at warming the atmosphere than carbon dioxide, comes from the stomachs of ruminants, such as cattle and sheep. Nitrous oxide, about 310 times more powerful than CO2, comes from the soil in wheat, maize, rice and sugar cane crops.

Eckard, who also works for the Victorian state government, said Australia had launched a national effort to find ways of tackling methane and nitrous oxide (N2O) emissions.

He leads a team that focuses mainly on intensive livestock systems and N2O emissions from wheat and grazing.

He said steps under development in Australia included dietary supplements and vaccines that curb methane production in livestock, as well as improving the rate, source and timing of nitrogen fertiliser use.

"We've evaluated oils and found out that for every one percent extra oil we put in the diet of a ruminant you get about a six percent reduction in methane," he said, referring to cottonseed and canola oil.

There was also a major project to breed a super variety of sheep and beef and dairy cattle that need less food to grow.

Scientists are also developing crop varieties that need less water and nitrogen fertiliser, Eckard said.

(Editing by Valerie Lee)

AlertNet news is provided by