Speaking exclusively to Rural Press following his address in Canberra to the National Press Club, Professor Garnaut said not having the measurements right for soil carbon was one of the reasons he recommended "not to go quickly" with agriculture.

He has recommended in his report to the Federal Government that the agriculture sector be initially left out of an emissions trading scheme.

"It's very important that the arrangements put in place give true credit for carbon that is in the soil," Professor Garnaut said.

"That's one of the reasons we can't go quickly with agriculture is because we're still working out how to measure that."

He said the amount of carbon which that could be stored in the soil "could be very big".

"Getting the measurement right, the administration right is crucial and a lot is going to be depending on that," he said.

"But my view is we shouldn't be moving to put agriculture in until we've got that right."

Professor Garnaut told the press club there would be winners and losers from the introduction of an emissions trading scheme, but would not say which of those would apply to agriculture.

He said it would be very important sheep and cattle industries were given some assistance once agriculture is included in a scheme, because despite being considerable emitters, they were also significantly trade exposed.

While the agriculture sector has argued that Kyoto agreement accounting rules should be changed to give greater recognition to the life cycle of farming and farming's contribution to reducing emissions, Professor Garnaut said we should forget Kyoto if the measurements in agriculture can be perfected.

"I think we can move ahead of the Kyoto rules," Professor Garnaut said.

"If we think we can measure things right, we can go ahead, even if the international community doesn't recognise it.

"It will be some cost for us but I think we should do it.

"But we've got to get it right, and if we can get it right then that could be an example to the world."

* Click here to read the full Garnaut report.