The Indiana Farm Bureau president says ethanol now accounts for 40 percent of the state's corn production.
A recent study indicates creating ethanol from corn releases 7 percent more carbon dioxide emissions than gasoline.
The EPA is proposing a reduction in the amount of ethanol in gasoline, which would be detrimental to Indiana corn farmers.
Chris Hurt testified Thursday before the US House of Representatives Energy and Power Subcommittee.
A computer simulation of the corn belt shows corn yields are likely to decline over the next several decades.
The Indiana Department of Environmental Management was letting ethanol plants in the state release more than two times EPA-allowed emissions.
Two of Indiana's largest ethanol plants have recently shut down because of a rapid increase in corn prices.
The lieutenant governor debate held at the Indiana State Fair focused on agricultural issues.
If the drought continues, corn produce could be too low to meet food and ethanol demands.
Indiana produces a significant amount of biofuels that could potentially be used in commercial and military airplanes.