NATIONAL Farmers' Federation president Jock Laurie is reluctant to voice an opposition to the proposed carbon tax.

Speaking at a Rural Press Club of Victoria lunch, Mr Laurie was questioned about whether the NFF supported a carbon tax.

Mr Laurie described it as a tax on food production because of the associated fuel costs.

"All our membership groups are sending the message that they oppose the tax," Mr Laurie said.

``But I'm not going to say we oppose the tax as we have to work with the crossbenchers on this.''

Mr Laurie had earlier said the NFF came across as climate change ``deniers'' if they opposed the carbon tax.

``Forget about the science.  I don't understand it,'' he said.

``The government has decided they want to do something, but if we question it then we are seen as deniers.''

Mr Laurie said farmers had been active in increasing the carbon stored in soil and making their farms more efficient.

He said an enormous amount of work had been done with planting trees as part of Landcare an the result was the storage of more carbon.

Mr Laurie said farmers had also improved the conversion rates of cattle.

``What industries have done what we have done to save water and store carbon?''