CEDAR RAPIDS (AP) — When Iowa farmers were done harvesting this year’s drought-stunted 2012 corn crop this fall, many of them didn’t stop there.

They returned to the fields to chop and rake the dried cornstalks into round bales that, at first glance, don’t look much different from hay bales.

The material is known as corn stover. Experts say farmers began harvesting more of it in the last few years of rising hay and grain prices, and harvested a lot more of it this year as the 2012 drought drove hay prices to record levels.