A new study confirms what most people involved in U.S. agriculture thought already: Crop diversity is declining, as many farmers increasingly focus on corn and soybeans.
The study, published recently in the scientific journal PLOS ONE and conducted by a handful of ag scientists from the Upper Midwest, finds crop diversity nationwide is significantly lower than it was 30 years ago.
That lessening of diversity has important implications for crops' resistance to drought, disease and insects, as well as for the environment, the report finds.
"Crop diversity is important for several reasons," says John Hendrickson, research rangeland management specialist with the U.S. Department of Agriculture's Agricultural Research Service's Northern Great Plains Research Laboratory in Mandan, N.D., and one of the report's authors. "If you increase your crop diversity, you spread your risk out over multiple crops. It also provides some benefits potentially to soil health," as well as helping bees and other pollinators, reducing runoff and providing more habitat for wildlife, among other things.
Other scientists involved in the project include: Greta Gramig, North Dakota State University; Mark Liebig and David Archer, Northern Great Plains Research Laboratory; Frank Forcella, ARS North Central Soil Conservation Research Lab in Morris, Minn.; and Jonathan Aguilar, Kansas State University, who worked previously at the Northern Great Plains Research Lab.
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The report uses county-level data from USDA's Census of Agriculture, which is conducted every five years, from 1978 to 2012.
A number of factors, including changes in ag policies and the development of new ag technologies, contributed to the increase in less-diverse cropping systems, the report finds.
Though the report takes a national perspective, it focuses, in part, on North Dakota. It notes that farmers in the state, on balance, are planting much more corn and soybeans, and fewer small grains, than they did 30 years ago.
But there are pockets in the state where diversity has increased. The growing popularity of no-till farming practices and increasing problems with Fusarium Head Blight led farmers in central North Dakota to plant a wider range of crops, Hendrickson says.
And while the overall national trend was less crop diversity, the Mississippi Portal Region, which includes parts of Mississippi, Louisiana, Kentucky and Arkansas, raised its crop diversity in the period measured.
Many farmers in the Upper Midwest are showing greater interest in long-term soil health in recent years, and attention of the benefits of crop diversity is growing. Hendrickson says the report doesn't look at that and he's unable to address it.
To see the PLOS One study, click here .
