THE Coalition is planning to pay farmers to store carbon in their fields for just 25 years in its bid to use soil carbon to meet 60 per cent of Australia's efforts towards long term greenhouse gas reduction.
Almost all existing greenhouse schemes require carbon-reducing land use changes to remain in place for 100 years but farmers were reluctant to modify their practices for such a long time, particularly for the very low prices proposed in the Coalition's ''Direct Action'' plan.
''Our preferred option is to give farmers a choice of either a 100-year or 25-year time frame, the latter of which doesn't lock up land for generations,'' a spokeswoman for the opposition climate spokesman, Greg Hunt, said.
Experts say shorter abatement pledges certainly would be more attractive to farmers but would transfer a big long-term liability to the federal government because it would have to find replacement ways to reduce greenhouse emissions after the 25-year contracts expired.
A partner in the law firm Baker and McKenzie, Martijn Wilder, said by allowing temporary reductions the Coalition was ''either banking on the idea that in 25 years the problem will have gone away or that by then they will have come up with a better answer''.
Andrew Macintosh, of the Australian National University centre for climate law and policy, said the Coalition's aim of achieving 60 per cent of its greenhouse reduction target from soil carbon was ''unrealistic'', and it should pay farmers even less for the 25-year contracts because the government was taking on a bigger risk.
But carbon farming groups say that even for a temporary 25-year reduction they would need to be paid much more than the $8 to $10 per tonne the Coalition has budgeted in its $10.5 billion ''Direct Action'' policy. The Opposition Leader, Tony Abbott, has said not a dollar more would be spent over the 10 years of the scheme.
Michael Kiely, of Carbon Farmers of Australia, said farmers were very pleased to be offered a ''more realistic'' 25-year timeframe, but would still need to be paid a lot more than $10 a tonne to take the offer up.
''I'd rather get $100 a tonne because I understand what it means,'' he said.
But Norman Marshall, the director of Australian Soil Management, said his company was ''finding it very difficult at the moment to convince farmers that changing their soil management was worth their while''.
If the Coalition introduced 25-year credits ''at around the $10 mark … that should do it,'' he said.
Farmers can increase the quantity of carbon stored in soils by different agricultural practices, tilling methods and by deliberately introducing a charcoal-like substance called biochar. But scientists are still working on how to measure the amount of carbon stored and understanding how it might be reversed by drought or fire.
A few forestry projects have been allowed to offer temporary 10-year credits as part of the international clean development mechanism, but demand for them has been low and such credits are not allowed in the European Union trading scheme.
Mr Macintosh said the Coalition was ignoring more promising sources of land use greenhouse abatement from reforestation or reductions in land clearing for agricultural purposes.