Kirschenmann, a distinguished fellow at the Leopold Center for Sustainable Agriculture at Iowa State University, defines sustainability as how to keep going indefinitely, but remaining sustainable even 10 years from now, will mean changes.


"We all talk about alternative energy, but I don't hear people talking about making an energy transition," Kirschenmann said. "We have to move from an energy input system to an energy exchange system."

Agriculture and other industries are based on a system of easily extracted fossil fuel.

"We tap into the earth's crust, pull it out and process it," Kirschenmann said. "Up until we reached peak oil in the 1970s, we were getting 100 kilocalories of energy for every kilocalorie we invested. Our whole economy was based on cheap energy."

Today very kilocalorie invested generates just 20 kilocalories.

There is growing interest in alternative energy, but people assume they will be able to produce enough to keep doing what they've always done.

"That's not true," Kirschenmann said. "The most efficient alternative, wind, generates 15 kilocalories for every kilocalorie used."

The current agricultural system is dependent on fossil energy for fuel, fertilizer, farm equipment and pesticides.