미국 농작물 수확의 변화

America’s heartland has a sameness that didn’t exist a generation ago. The amber waves of grain are still there, and the corn’s still as high as an elephant’s eye—but they’re less and less likely to exist side by side.

As global markets have grown, the desire and need for diverse local production has declined. There’s no need for a little wheat here or a few cows there when agriculture has gone industrial-scale. The result has literally shifted the American landscape.

Since the mid-1990s, around the time that genetically modified crops became prevalent in U.S. agriculture, the diversity of American fields has decreased. It’s not just the GMOs, although they have aided the spread of corn and soybeans. The rise of ethanol and farm exports to China—as well as cheaper transportation costs, increasing regional concentration of livestock feedlots, and climate change—have each played a role.

Here’s where it’s happened. Each map below shows the rise ↑ or fall ↓ in percentage terms of a county’s total acreage devoted to corn, soybeans, wheat or cotton from 1995 through last year. At the bottom is a group of maps for barley, oats, rice and sorghum, regional crops also affected by the shift.

Go West, Corn Crop!

50%

30

10

Percent change in planted acres

The production region informally known as the Corn Belt—traditionally characterized as beginning somewhere in Ohio and ending at the edge of the Great Plains—needs a new definition. Acreage has dropped off in parts of the east, including Indiana, Ohio and Michigan. Meanwhile, production has spilled west into the Dakotas, inched north in Minnesota and spread across Missouri. A mini-corn boom has occurred along a swath of the East Coast from eastern Pennsylvania into the Carolinas, as well as in counties along the Mississippi River.

The Rise of the Soybean

Corn remains the top U.S. crop in dollar value and production. But this year it lost its crown as the most-planted agricultural product after being surpassed by soybeans for the first time in 35 years.

Soybeans thrive in the same climate as corn, and both crops are frequently rotated to keep soil healthy. Soy cultivation has risen in corn areas. In many places the switch to soy has been dramatic. Oilseed acreage has grown in places like Ohio, Michigan and Wisconsin, where corn has been declining. Soybeans benefit from many of the same factors that support corn demand, although soy-based biodiesel production is nowhere near that of ethanol derived from corn. Soybeans, however, have one big driver corn lacks: China. Chinese import volumes of U.S. soybeans increased more than 15,000 percent from 1995 through 2017, raising the oilseed to co-preeminence with corn.

Whither Wheat?

The big loser from corn and soy’s gain is wheat. The most-planted U.S. crop as recently as 1990, wheat has come under pressure on several fronts: competition from growers in the Black Sea region, the lack of GMO varieties and its ineffectiveness as cattle feed, compared with corn and soy. Other than a few isolated counties in the Plains,—where even GMO soybeans and corn won’t get enough rain—and a swath near the East Coast—where urbanites want locally grown bread and farmers are diversifying their crop rotations to control weeds—wheat acreage has been declining for a generation.

Cotton Retreats

Cotton, the icon of the American South, may be affected by Chinese trade as much as soybeans—but the cotton-export boom has been a mixed blessing for the U.S. economy. While exports to China have exploded, with the world’s biggest clothes producer buying one-third of the crop, the domestic textile industry has been decimated. That’s clear from the maps, where textile-producing regions in the southeast have seen acreage tumble.

Cotton’s only real growth has come from the western edge of the traditional Cotton Belt. Biotech varieties and water-saving technology have made the crop more viable in West Texas and Oklahoma, while warmer summers have pushed production into Kansas, where cotton was rare at the turn of the century.

Small Grains Shrink

Rice

Sorghum

Rising export demand for the biggest U.S. crops, along with biofuels, has come at the expense of grains that have long thrived through niche uses. Barley, still viable for beer, is used less for food and feed on the Northern Plains as corn and soy have come in. Oats have less use as Canada supplies more U.S. needs and warmer-weather plants have become more competitive further north. U.S. rice, limited to the Mississippi Delta and parts of California, has contracted even further into a few counties where it continues to offer strong economic returns. And sorghum, which is more climate-proof but lower-yielding than corn, is becoming more concentrated in western Kansas—losing its place in rotations elsewhere while maintaining viability through growth in China sales.

Where will U.S. fields go next? If past is prologue, production of minor crops will continue to become more constricted, wheat will become ever-less competitive and soy will rise and fall with Chinese buying habits. Still, disruptions remain possible, shifting both short- and long-term trends. With a trade war continuing to crimp soybean exports, a 2019 map will likely see a soy retrenchment and corn reasserting itself. At some point, improved wheat varieties could see the amber waves make a comeback. Climate demands could fuel more sorghum production—or the repeal of ethanol rules could roll back some of corn’s gains.

But nationwide, diversity isn’t likely to come back. Agriculture demands too much specialization in the 21st century, and regions of the U.S. are differentiating themselves based on what they grow best. Globalization ebbs and flows, but probably can’t be completely reversed. You can feel it in the nation’s fields. Or, you can see it out your window, as you journey to a different place.

https://www.bloomberg.com/graphics/2018-crop-shift/?cmpid=%3Dsocialflow-twitter-graphics