Oats and alfalfa to reduce Corn Belt erosion?

A corn field in Iowa at harvest.

A new study released by the Union of Concerned Scientists (UCS) found that modified three- and four-crop farming systems could be scaled up and adopted widely in Corn Belt states, generating benefits to farmers and taxpayers worth hundreds of millions of dollars.

The analysis builds on a long-term study at Iowa State University, known as the Marsden Farm study, which demonstrated that adding combinations of alfalfa, cover crops, and small grains such as oats to a typical corn-soy rotation can increase farmers’ yields and maintain profits while reducing herbicide and fertilizer use. The UCS analysis shows that pairing these longer rotations with soil-conserving no-till practices and scaling the system up strategically would have dramatic results.

Adoption of the no-till three-year or four-year rotation system, compared with tilled corn-soy, in the 25 Iowa counties with the most erodible soils would slash erosion by as much as 91 per cent.

For those counties, the diversified rotation would also keep fertilizers out of lakes and streams. Iowa taxpayers would see water pollution cleanup savings of nearly $200 million annually and net reductions in heat-trapping gases valued at up to $78 million annually.

Over time, and with the expansion of markets for oats or other small grains in the rotation, the system could be scaled up to nearly 40 per cent of Iowa’s current farmland without driving farmers back to predominantly corn-soy. Although the analysis focused on Iowa, the results can be generalized across the 12-state Corn Belt.

The longer rotation system would benefit farmers, who are increasingly squeezed by today’s dominant Midwest corn-and-soy system. U.S. growers of these crops achieved record-high harvests in 2016, but the prices farmers receive for these crops have plummeted; U.S. farm incomes for this year are expected to drop to their lowest levels since 2002. Diversifying production would leave farmers less vulnerable to such price shifts, and expanding markets for additional crops would create new business opportunities. In addition, the system improves farmers’ soils, ensuring they can keep farming into the future.

“Diversifying crop rotations is a win-win-win solution for farmer profits, the long-term health of their soil, and clean water for communities,” said Kranti Mulik, author of the report and senior economist at UCS. “If we want to multiply the benefits, though, we need to be able to scale these practices up across the region.”

The diverse rotation system works by keeping soil covered and undisturbed year round. This minimizes soil erosion and reduces the need for fertilizers and herbicides, which keeps pollutants out of lakes and streams. Every year, nitrogen use in U.S. agriculture causes $157 billion in environmental damage — more than double the value of the entire 2011 U.S. corn harvest — and taxpayers, fishing and recreation industries, and under-resourced water utilities pick up the tab.

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