One thing I’ve learned over the years: People outside of agriculture almost always underestimate American farmers’ ability to boost production, increase efficiency and lighten their footprint on the environment.

There was another example of that last week when a new U.S. Department of Agriculture (USDA) study showed greenhouse gas (GHG) emissions from  corn-based ethanol are much lower than earlier projected and are about 39 percent lower than gasoline.

Two big reasons for that are continued gains in farm productivity and wide-scale adoption of conservation practices,  according to the USDA researchers.

When ethanol came into its own 15 years ago, there were warnings that increased demand would prompt farmers to disk up lots of land to grow corn. That hasn’t happened.

Some land was bought into production or relocated to corn over the last 15 years, but other land was idled. Instead, a big factor in reducing GHG emissions was that farmers in Iowa and other states just kept getting better, steadily harvesting more grain off the same acres. The average Iowa corn yield rose 21 percent in the 15 years between 2004 and 2018.

Added to that, farmers are adopting conservation practices, including reduced tillage and cover crops, as they take on the challenge of improving water quality and reducing soil loss. Those changes, according to the USDA report, are also helping reduce GHG emissions.

It’s a good story that may surprise many, especially those who continue to underestimate farmers.