OTTAWA -- The federal government says its analysis of the impact the carbon tax is having on grain farmers is based on numbers provided by the farmers themselves.

But grain farmers are adamant that Agriculture and Agri-Food Canada was wrong when it concluded this week grain farmers were, at most, paying $819 a year in carbon tax to dry their corn, wheat, barley and other grains.

Markus Haerle, chair of the Grain Farmers of Ontario, says the carbon tax bill for drying corn from his 800-hectare farm in St. Isidore, Ont., was $8,500 last fall, and that he is not alone.

After a wet and late spring, and an early snowfall in the autumn, grain farmers in the Prairies and Ontario found themselves turning to grain dryers more than usual, at the same time most of them were starting to pay the carbon tax on the propane or natural gas they used.

Farmers are lobbying Ottawa hard to give grain dryers the same exemption to the carbon tax that applies to fuels used to run farm vehicles or the partial exemption offered for fuels to heat commercial greenhouses.

Agriculture Minister Marie-Claude Bibeau says the government is supporting efforts to improve the energy efficiency of grain dryers, including a new $2-million joint program with Alberta that covers up to half the cost of upgrading the machines.