In the United States, corn uses more land than any other crop, spanning some 97 million acres —  an area roughly the size of California. U.S. corn also consumes a large amount of our freshwater resources, including an estimated 5.6 cubic miles per year of irrigation water withdrawn from America’s rivers and aquifers. And fertilizer use for corn is massive: over 5.6 million tons of nitrogen is applied to corn each year through chemical fertilizers, along with nearly a million tons of nitrogen from manure. Much of this fertilizer, along with large amounts of soil, washes into the nation’s lakes, rivers and coastal oceans, polluting waters and damaging ecosystems along the way. The dead zone in the Gulf of Mexico is the largest, and most iconic, example of this.

And the resources devoted to growing corn are increasing dramatically. Between 2006 and 2011, the amount of cropland devoted to growing corn in America increased by more than 13 million acres, mainly in response to rising corn prices and the increasing demand for ethanol. Most of these new corn acres came from farms, including those that were growing wheat (which lost 2.9 million acres), oats (1.7 million acres lost), sorghum (1 million acres lost), barley, alfalfa, sunflower and other crops. That leaves us with a less diverse American agricultural landscape, with even more land devoted to corn monocultures. And according to a recent study published in the Proceedings of the National Academy of Sciences, roughly 1.3 million acres of grassland and prairie were converted to corn and other uses in the western Corn Belt between 2006 and 2011, presenting a threat to the waterways, wetlands and species that reside there.

This isn’t rocket science: You wouldn’t invest in a mutual fund that was dominated by only one company, because it would be intolerably risky. But that’s what we’re doing with American agriculture.

Looking at these land, water, fertilizer and soil costs together, you could argue that the corn system uses more natural resources than any other agricultural system in America, while providing only modest benefits in food. It’s a dubious trade-off — depleting natural resources to deliver relatively little food and nutrition to the world. But it doesn’t need to be that way. Innovative farmers are exploring other methods for growing corn, including better conventional, organic, biotech and conservation farming methods that can dramatically reduce chemical inputs, water use, soil losses and impacts on wildlife. We should encourage American farmers to continue these improvements.

The Corn System Is Highly Vulnerable to Shocks. While a large monoculture dominating much of the country with a single cropping system might be an efficient and profitable way to grow corn at an industrial scale, there is a price to being so big, with so little diversity. Given enough time, most massive monocultures fail, often spectacularly. And with today’s high demand and low grain stocks, corn prices are very volatile, driving spikes in the price of commodities around the world. Under these conditions, a single disaster, disease, pest or economic downturn could cause a major disturbance in the corn system.

The monolithic nature of corn production presents a systemic risk to America’s agriculture, with impacts ranging from food prices to feed prices and energy prices. It also presents a potential threat to our economy and to the taxpayers who end up footing the bill when things go sour. This isn’t rocket science: You wouldn’t invest in a mutual fund that was dominated by only one company, because it would be intolerably risky. But that’s what we’re doing with American agriculture. Simply put, too many of our agricultural eggs are in one basket.

A more resilient agricultural system would start by diversifying our crops, shifting some of the corn monoculture to a landscape rich with a variety of crops, pastures and prairies. It would more closely mimic natural ecosystems and include a mixture of perennial and different seasonal plants — not just summertime annuals with shallow roots that are especially sensitive to dry spells. Furthermore, it would include conservation tillage and organic farming practices that improve soil conditions by restoring soil structure, organic content and water holding capacity, making farming landscapes much more resilient to floods and droughts. The overall result would be a landscape better prepared to weather the next drought, flood, disease or pest.

The Corn System Operates at a Big Cost to Taxpayers. Finally, the corn system receives more subsides from the U.S. government than any other crop, including direct payments, crop insurance payments and mandates to produce ethanol. In all, U.S. crop subsidies to corn totaled roughly $90 billion between 1995 and 2010 — not including ethanol subsidies and mandates, which helped drive up the price of corn.