Crop Diversity Is Dwindling In U.S., Study Shows

A long-term study finds the U.S. crop supply is becoming less and less diverse and monoculture farms are taking precedence.

by Dani Yokhna

A study shows the loss of crop diversity in the U.S. over the past three decades.

What do you learn when you’re developing investment portfolios? Diversify. Formulating a diet? Diversify. Planning crops for anything other than a monoculture? Diversify. Our world requires diversity.

The basic tenets of sustainable farming include crop diversification and crop rotation for soil nutrient content, soil organic matter, pest control and tilth. So why is it that this country has way less crop diversity than it needs—and it’s tanking further every year?

34 Years of Monocultures

Thirty-four years ago, farmers grew a more diverse group of crops than they do now, and the trend is that crop diversity continues to dwindle. That sucks for a number of reasons. For one, see the benefits of crop diversity I mentioned above. Second, less diversity means less ability to deal with climate changes on the farm. And finally, the ecosystem at large may be impacted, according to a study by Kansas State University, North Dakota State University and the USDA.

With 22 percent of the contiguous U.S. in crop acreage, what’s planted there has quite an impact—not only on our diets but on the natural and developed areas around it.

“At the very simplistic level, crop diversity is a measure of how many crops in an area could possibly work together to resist, address and adjust to potential widespread crop failures, including natural problems, such as pests and diseases, weed pressures, droughts, and flood events.” says Jonathan Aguilar, Kansas State water resources engineer and lead researcher on the study. “This could also be viewed as a way to spread potential risks to a producer. Just like in the natural landscape, areas with high diversity tend to be more resilient to external pressures than are areas with low diversity. In other words, diversity provides stability in an area to assure food sustainability.”

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This is something I saw first-hand during the growing season this year, when six weeks of rain decimated many of the crops growing on the farm. The ones that survived weren’t thriving but managed to pull the farm through a really tough time. Crop diversity is sustainable farming’s answer to crop insurance.

How’s Your Region’s Diversity?

While the overall news of the KSU/NDSU/USDA study is not encouraging, there are some areas of the country that are doing better than others.

  • The region of Illinois, Iowa, Indiana and parts of Ohio, Missouri, Minnesota, South Dakota, Nebraska and Kentucky features 22 percent of U.S. farms and the highest value of farm production. It has the lowest crop diversity. It’s sad—but not surprising—to learn this.
  • Parts of Louisiana, Mississippi, Kentucky and Arkansas had significantly higher crop diversity in 2012 than in 1978. Good job, guys!
  • Parts of Washington, Oregon, Idaho, California, Arizona, Texas, Florida, Georgia and South Carolina, plus states along the northeast border from part of Minnesota east through Wisconsin, Michigan through to Maine, and south to New Jersey and Pennsylvania have the most crop diversity. Keep it up!

The full, peer-reviewed study is available online if you’d like to dig deeper into what’s happening in your area and around the country.

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