Another vote for sorghum for biofuel

It’s hard to know whether sorghum is getting increasing attention as a possible biofuel source because it makes sense as a solution to our energy and environment challenges, or mostly because it could boost Midwest farm economies.

Last year we reported that researchers at Kansas State had won an $800,000 grant from the U.S. departments of Agriculture and Energy for a three-year study intended to provide the genetic groundwork necessary for potentially turning sorghum into biofuel by increasing the plant’s biomass yield.

Now Purdue University, in Indiana, is out with new research touting sorghum as a feedstock for cellulosic biofuel. These are sometimes referred to as “next-generation” biofuels because they move beyond using corn to make ethanol and shift toward using feedstocks that have lower carbon footprints and don’t draw resources away from food production.

The Purdue researchers argue that sorghum could require fewer inputs than corn, and could also be grown on marginal lands.

“In the near future, we need a feedstock that is not corn,” says Cliff Weil, a Purdue professor of agronomy. “Sweet and biomass sorghum meet all the criteria. They use less nitrogen, grow well and grow where other things don’t grow.”

A key, the scientists say, is that corn has been bred over the years to produce as much seed as possible, and growing seeds eats up nitrogen. Sorghum could turn that equation around by emphasizing cellulose production. “If you’re just producing biomass and not seed, you don’t need as much nitrogen,” says Nick Carpita, a Purdue professor of botany and plant pathology.

Other materials also produce lots of cellulose, like perennials switchgrass and Miscanthus, but the Purdue scientists say sorghum has some advantages there: as an annual it could fit in with a normal crop rotation, unlike the perennials that would take up a field for a decade or longer (this was something Penn State researchers promoting sorghum have also pointed to); farmers are familiar with it; and an infrastructure for sorghum production and processing already exists, making it a more cost-effective option.

But as compelling as the case laid out by the Purdue team sounds, it’s hard not to wonder whether this isn’t just another case of the Midwest ag establishment seeking out an economic opportunity. That is, after all, what these big university’s research departments are charged with doing.

Farzad Taheripour, a Purdue research assistant professor of agricultural economics, might be right that sorghum-for-biofuel could “significantly improve the economy of rural areas that rely on low-productivity agriculture,” but does it pencil out as a national or international strategy? That’s the real question.

* Pete Danko, EarthTechling