Growing crops for ethanol causes global warming?

Francis Thicke, an organic dairy farmer from Fairfield, Iowa, who has a Ph.D. in soil fertility, said he provides his 130 animals with grassy areas to forage for food. That cuts down on fuel needs because he's not growing as much grain for feed, and it allows carbon to remain in the soil because there's no need for tilling.

Thicke said politicians should end subsidies to farmers who grow crops such as corn and soybeans that rob the soil of nutrients and require lots of energy.

"Our whole farming system really contributes a lot to global warming, and it could be made to be much more sustainable," he said. (more)

One of my biggest questions about ethanol has long been how much pollution is caused by pesticides and fertilizers, especially to groundwater and as runoff into streams, rivers and lakes, but I had no idea that simply tilling the soil could contribute to global warming.

It seems that other crops, such as hemp or switchgrass, might overcome these limitations as cellulosic ethanol processing is perfected. Still, will big agri-business favor corn over these other sources because of government subsidies.

Ethanol. I'm still not sure I'm very convinced.