Benefits seen to planting many crops
Corn and soybeans are America’s biggest, most important crops. They have many uses — from kitchen tables to industrial plants, from feedlots to fuel tanks — and they add billions of dollars annually to the farm economy.
“There are benefits to crop diversity, in going beyond corn and soybeans,” says Scott Fausti, an ag economist at South Dakota State University.
He and Jonathan Lundgren, a U.S. Department of Agriculture research entomologist in Brookings, led a two-year project that assessed insect populations in cornfields on 53 farms, both conventional and organic, in eastern South Dakota. Their 10-person team dissected approximately 2,650 plants and identified more than 37,000 insect specimens.
When they counted the different bugs, the researchers found that fields with more crop diversity had fewer pests, Lundgren says. Fields with many different insects had fewer bugs that damage crops, reflecting the connection between bugs that eat crops and bugs that eat other bugs.
“The research suggests, farm management practices that enhance biodiversity will experience fewer pest problems,” Lundgren says.
That, in turn, will reduce pesticide use and production costs, Fausti says.
Planting a wider range of crops also “makes producers less vulnerable to swing in crop prices,” he says. “Crop diversity is about not putting all your eggs in one basket.”
‘What’s best for their area’
Keith Alverson knows as much as anyone about growing just corn and soybeans. The Chester, S.D., farmer and his family plant about 85 percent of their acres every year to corn, the rest to soybeans.
Though he’s not familiar with Fausti and Lundgren’s research, Alverson understands growing a number of crops can be useful.
“Time has shown that it (crop diversity) can help you break up the pest cycle, the weed cycle,” Alverson says. “There are definite benefits to diversity.”
He also understands that planting a number of crops can help spread economic risk.
On the other hand, there’s solid research that shows “planting a lot of high-residue crops like corn builds up organic matter in your soil and benefits soil health,” says Alverson, president of the South Dakota Corn Growers Association.
And the value of spreading economic risk with crop diversity is greater in areas where weather and soil types lessen the odds of harvesting a good crop, he says.
“In some places, diversity is more common,” he says. “(In) high-rainfall areas, maybe ones that have a little more consistent soil types, you tend to see lower diversity.”
Farmers in much of southern Minnesota, eastern South Dakota and southeast North Dakota, where rainfall and soil are relatively favorable, are more likely to plant just corn and beans. Producers in northwest Minnesota and the western Dakotas, where weather and soil are more variable, tend to plant a wider range of crops.
“Farmers try to do what’s best for their area, what’s right for their farm and soil,” Alverson says.
“We all need to be economically viable,” he says. “Diversity can be beneficial, but we need to be profitable enough to stay in business until the next year.”
Farmers will continue to weigh all the factors, including new research, in making their planting decisions, he says.
“We may not adopt it (new research) overnight, but eventually we’ll do what’s right,” he says.
At least two other studies come to the same basic conclusion as the work done by Lundgren and Fausti.
A team of Upper Midwest scientists recently released a study that finds crop diversity nationwide is significantly lower than it was 30 years ago. It also found that less diversity affects crops’ resistance to drought, disease and insects, and also has important implications for the environment.
Increasing diversity spreads out risk, potentially enhances soil health, helps bees and other pollinators, reduces runoff and provides more wildlife habitat, among other benefits, says John Hendrickson, research rangeland management specialist with USDA Agricultural Research Service’s Northern Great Plains Research Laboratory in Mandan, N.D., and one of the report’s authors.
Another study, by Iowa’s Leopold Center for Sustainable Agriculture, examined a decade of research into corn-soybean rotations and diverse rotations. It found that a diverse rotation, on average, produced 4 percent higher corn yields and 9 percent higher soybean yields.
Diverse rotations also featured far less use of synthetic nitrogen and effective weed control with much less herbicide, according to the 2012 Leopold Center study.
At wheat’s expense
Corn and soybeans have become so popular they were planted on more than half of all U.S. crop acres over the past five years. Corn accounted for 30 percent of planted acres and soybeans were 24 percent.
Typically, farmers rotate the two crops on a field, planting corn one year and soybeans the next year. But corn-on-corn and soybeans-on-soybeans — planting the same crop over and over on the same field — isn’t unusual.
As Fausti puts it, “The corn-soybean monoculture cropping system has become a dominant fixture in modern crop production in the U.S.”
Advances in biotechnology and the growing use of ethanol made from corn have encouraged farmers to grow more corn and soybeans, he says.
Exceptionally strong corn prices a few years ago also led farmers, especially in parts of North Dakota, South Dakota and northwest Minnesota, where the crop isn’t well established, to grow more of it.
Much of the rise in corn and soybean acreage has come at the expense of wheat.
Planted U.S. wheat acres from 69 million in 1995 to 55 million in 2015. In the same 20-year period, U.S. planted corn acreage rose from 79 million to 88 million and U.S. planted soybean acreage increased from 62 million to 83 million.
The National Association of Wheat Growers is developing a broad-scale, industry-wide plan to increase wheat acres. Farmers will be surveyed this winter and the plan will be formulated in about a year, Brett Blankenship, a wheat farmer from Washtucna, Wash., and president of the National Association of Wheat Growers, told Agweek earlier this fall.
Wheat and other cereal grains are among the candidates for farmers who want to expand their rotation beyond corn and soybeans, Fausti says.