WASHINGTON (Reuters) - U.S. corn used to produce ethanol will increase in 2009/10, but beyond that, growth is forecast to slow with demand mirroring changes in gasoline consumption, the Agriculture Department said on Thursday.

USDA projected 4.2 billion bushels of corn will be used to produce ethanol in 2009/10, an increase from 3.6 billion bushels forecasted for the current year.

Overall, ethanol is forecast to command about 33 percent of the corn crop compared to 30 percent in 2008/09.

"While expansion in the ethanol industry continues, smaller gains for corn-based ethanol are projected, largely reflecting moderate growth in overall gasoline consumption in the United States," USDA said in its annual "baseline" report.