OMAHA, Neb. — New research shows that prairie grasses grown using only moderate amounts of fertilizer on marginal land can produce significant amounts of ethanol.

The five-year study of switch grass done by the University of Nebraska and the USDA's Agricultural Research Service was published this week by the National Academy of Sciences.

Researcher Ken Vogel said he estimates that an acre of switch grass would produce an average of 300 gallons of ethanol based on the study of grass grown on marginal land on farms in Nebraska, South Dakota and North Dakota.

An acre of corn grown in those same states produces about 350 gallons of ethanol on average.

Vogel said this switch grass research is the most extensive to date.

Both cellulosic and grain-based ethanol will likely play a role in meeting the new federal standard for biofuel use. The energy bill Congress passed last month requires a massive increase in the production of ethanol to 36 billion gallons a year by 2022.

The energy bill will emphasize cellulosic ethanol, made from such feedstock as switch grass and wood chips, after 2015 when about two-thirds of the nation's ethanol is supposed to come from such non-corn sources.

Vogel said comparing the amount of ethanol produced by corn with the amount that could be produced by switch grass is a bit unfair because the method of converting switch grass to fuel is still being perfected.

Last year, the Department of Energy announced plans to invest $385 million in six ethanol refineries across the country to jump-start ethanol production from cellulose-based sources, a process that has not yet been proven commercially viable.