This essay was posted simultaneously at Scientific American.

Nothing dominates the American landscape like corn.

Sprawling across the Midwest and Great Plains, the American Corn Belt is a massive thing. You can drive from central Pennsylvania all the way to western Nebraska, a trip of nearly 1,500 miles, and witness it in all its glory. No other American crop can match the sheer size of corn.

So why do we, as a nation, grow so much corn?

The main reason is that corn is such a productive and versatile crop, responding to investments in research, breeding and promotion. It has incredibly high yields compared with most other U.S. crops, and it grows nearly anywhere in the country, especially thriving in the Midwest and Great Plains. Plus, it can be turned into a staggering array of products. Corn can be used for food as corn flour, cornmeal, hominy, grits or sweet corn. It can be used as animal feed to help fatten our hogs, chickens and cattle. And it can be turned into ethanol, high-fructose corn syrup or even bio-based plastics.

No wonder we grow so much of the stuff.

But it is important to distinguish corn the crop from corn the system. As a crop, corn is highly productive, flexible and successful. It has been a pillar of American agriculture for decades, and there is no doubt that it will be a crucial part of American agriculture in the future. However, many are beginning to question corn as a system: how it dominates American agriculture compared with other farming systems; how in America it is used primarily for ethanol, animal feed and high-fructose corn syrup; how it consumes natural resources; and how it receives preferential treatment from our government.

The current corn system is not a good thing for America for four major reasons.

The American Corn System Is Inefficient at Feeding People. Most people would agree that the primary goal of agriculture should be feeding people. While other goals — especially producing income, creating jobs and fostering rural development — are critically important too, the ultimate success of any agricultural system should be measured in part by how well it delivers food to a growing population. After all, feeding people is why agriculture exists in the first place.

The corn system is aligned to feed cars and animals instead of feeding people.

While U.S. corn is a highly productive crop, with typical yields between 140 and 160 bushels per acre, the resulting delivery of food by the corn system is far lower. Today’s corn crop is mainly used for biofuels (roughly 40 percent of U.S. corn is used for ethanol) and as animal feed (roughly 36 percent of U.S. corn, plus distillers grains left over from ethanol production, is fed to cattle, pigs and chickens). Much of the rest is exported. Only a tiny fraction of the national corn crop is directly used for food for Americans, much of that for high-fructose corn syrup.

Yes, the corn fed to animals does produce valuable food to people, mainly in the form of dairy and meat products, but only after suffering major losses of calories and protein along the way. For corn-fed animals, the efficiency of converting grain to meat and dairy calories ranges from roughly 3 percent to 40 percent, depending on the animal production system in question. What this all means is that little of the corn crop actually ends up feeding American people. It’s just math. The average Iowa cornfield has the potential to deliver more than 15 million calories per acre each year (enough to sustain 14 people per acre, with a 3,000 calorie-per-day diet, if we ate all of the corn ourselves), but with the current allocation of corn to ethanol and animal production, we end up with an estimated 3 million calories of food per acre per year, mainly as dairy and meat products, enough to sustain only 3 people per acre. This is lower than the average delivery of food calories from farms in Bangladesh, Egypt and Vietnam.

In short, the corn crop is highly productive, but the corn system is aligned to feed cars and animals instead of feeding people.

There are a number of ways to improve the delivery of food from the nation’s corn system. First and foremost, shifting corn away from biofuels would generate more food for the world, lower demand for grain, lessen commodity price pressures, and reduce the burden on consumers around the world. Furthermore, eating less corn-fed meat, or shifting corn toward more efficient dairy, poultry, pork and grass-fed beef systems, would allow us to get more food from each bushel of corn. And diversifying the Corn Belt into a wider mix of agricultural systems, including other crops and grass-fed animal operations, could produce substantially more food — and a more diverse and nutritious diet — than the current system.

The Corn System Uses a Large Amount of Natural Resources. Even though it does not deliver as much food as comparable systems around the globe, the American corn system continues to use a large proportion of our country’s natural resources.