More Sustainable Feedstock for Ethanol

A six-year Great Lakes Bioenergy Research Center (GLBRC) study on the viability of different bioenergy feedstocks recently demonstrated that perennial cropping systems such as switchgrass, giant miscanthus, poplar, native grasses and prairie can yield as much biomass as corn stover.

The study is significant for addressing one of the biofuel industry’s biggest questions: Can environmentally beneficial crops produce enough biomass to make their conversion to ethanol efficient and economical?

Since 2008, research scientists Gregg Sanford and Gary Oates, based in the lab of CALS agronomy professor Randy Jackson, have worked with colleagues at Michigan State University (MSU) to cultivate more than 80 acres of crops with the potential to become feedstocks for so-called “second-generation” biofuels, that is, biofuels derived from non-food crops or the nonfood portion of plants. They’ve grown these crops at the CALS-based Arlington Agricultural Research Station and at MSU’s Kellogg Biological Station.

“We understand annual systems really well, but little research has been done on the yield of perennial cropping systems as they get established and begin to produce, or after farmland has been converted to a perennial system,” says Oates.

To find out basic information about how well certain crops produce biomass, Sanford and Oates tested the crops across two criteria: diversity of species, and whether a crop grows perennially (continuously, year after year) or annually (needing to be replanted each year).

Highly productive corn stover has thus far been the main feedstock for second-generation biofuels. And yet perennial cropping systems, which are better equipped to build soil quality, reduce runoff, and minimize greenhouse gas release into the atmosphere, confer more environmental benefits.

Corn, when grain is included, proved to be most productive over the first six-year period of the study at the Wisconsin site, but giant miscanthus, switchgrass, poplar and native grasses were not far behind. At the MSU site, where soil is less fertile, miscanthus actually produced the same amount of biomass as corn (grain included) in the experiment, with poplar and switchgrass within range.

“All of this means that, at large scales and on various soils, these crops are competitive with corn, the current dominant feedstock for ethanol,” Sanford says.

Now in the midst of the study’s eighth year, Sanford says the study will continue for the foreseeable future.

“We know that perennial systems can prevent negative impacts such as soil erosion and nitrate leaching, and that they also provide habitat for native species that provide beneficial ecosystem services,” Sanford says. “But there are still a lot of questions we want to answer about soil processes and properties— questions that take many years to answer.”

Researcher Gregg Sanford stands before a plot of giant miscanthus at Arlington.

Photo credit – Matthew Wisniewski

Plant Prowess

It may look jury-rigged, but it’s cutting-edge science.

In a back room in the university’s Seeds Building, researchers scan ears of corn—three at a time—on a flatbed scanner, the kind you’d find at any office supply store. After running the ears through a shelling machine, they image the de-kerneled cobs on a second scanner.

The resulting image files—up to 40 gigabytes’ worth per day—are then run through a custom-made software program that outputs an array of yield-related data for each individual ear. Ultimately, the scientists hope to link this type of information—along with lots of other descriptive data about how the plants grow and what they look like—back to the genes that govern those physical traits. It’s part of a massive national effort to deliver on the promise of the corn genome, which was sequenced back in 2009, and help speed the plant breeding process for this widely grown crop.

“When it comes to crop improvement, the genotype is more or less useless without attaching it to performance,” explains Bill Tracy, professor and chair of the Department of Agronomy. “The big thing is phenotyping—getting an accurate and useful description of the organism—and connecting that information back to specific genes. It’s the biggest thing in our area of plant sciences right now, and we as a college are playing a big role in that.”

No surprise there. Since the college’s founding, plant scientists at CALS have been tackling some of the biggest issues of their day. Established in 1889 to help fulfill the University of Wisconsin’s land grant mission, the college focused on supporting the state’s fledgling farmers, helping them figure out how to grow crops and make a living at it. At the same time, this practical assistance almost always included a more basic research component, as researchers sought to understand the underlying biology, chemistry and physics of agricultural problems.

That approach continues to this day, with CALS plant scientists working to address the ever-evolving agricultural and natural resource challenges facing the state, the nation and the world. Taken together, this group constitutes a research powerhouse, with members based in almost half of the college’s departments, including agronomy, bacteriology, biochemistry, entomology, forest and wildlife ecology, genetics, horticulture, plant pathology and soil science.

“One of our big strengths here is that we span the complete breadth of the plant sciences,” notes Rick Lindroth, associate dean for research at CALS and a professor of entomology. “We have expertise across the full spectrum—from laboratory to field, from molecules to ecosystems.”

This puts the college in the exciting position of tackling some of the most complex and important issues of our time, including those on the applied science front, the basic science front—and at the exciting new interface where the two approaches are starting to intersect, such as the corn phenotyping project.

“The tools of genomics, informatics and computation are creating unprecedented opportunities to investigate and improve plants for humans, livestock and the natural world,” says Lindroth. “With our historic strength in both basic and applied plant sciences, the college is well positioned to help lead the nation at this scientific frontier.”

It’s hard to imagine what Wisconsin’s agricultural economy would look like today without the assistance of CALS’ applied plant scientists.

The college’s early horticulturalists helped the first generation of cranberry growers turn a wild bog berry into an economic crop. Pioneering plant pathologists identified devastating diseases in cabbage and potato, and then developed new disease-resistant varieties. CALS agronomists led the development of the key forage crops—including alfalfa and corn—that feed our state’s dairy cows.

Fast-forward to 2015: Wisconsin is the top producer of cranberries, is third in the nation in potatoes and has become America’s Dairyland. And CALS continues to serve the state’s agricultural industry.

The college’s robust program covers a wide variety of crops and cropping systems, with researchers addressing issues of disease, insect and weed control; water and soil conservation; nutrient management; crop rotation and more. The college is also home to a dozen public plant-breeding programs—for sweet corn, beet, carrot, onion, potato, cranberry, cucumber, melon, bean, pepper, squash, field corn and oats—that have produced scores of valuable new varieties over the years, including a number of “home runs” such as the Snowden potato, a popular potato chip variety, and the HyRed cranberry, a fast-ripening berry designed for Wisconsin’s short growing season.

While CALS plant scientists do this work, they also train the next generation of researchers—lots of them. The college’s Plant Breeding and Plant Genetics Program, with faculty from nine departments, has trained more graduate students than any other such program in the nation. Just this past fall, the Biology Major launched a new plant biology option in response to growing interest among undergraduates.

“If you go to any major seed company, you’ll find people in the very top leadership positions who were students here in our plant-breeding program,” says Irwin Goldman PhD’91, professor and chair of the Department of Horticulture.

Among the college’s longstanding partnerships, CALS’ relationship with the state’s potato growers is particularly strong, with generations of potato growers working alongside generations of CALS scientists. The Wisconsin Potato and Vegetable Growers Association (WPVGA), the commodity group that supports the industry, spends more than $300,000 on CALS-led research each year, and the group helped fund the professorship that brought Jeff Endelman, a national leader in statistical genetics, to campus in 2013 to lead the university’s potato-breeding program.

“Research is the watchword of the Wisconsin potato and vegetable industry,” says Tamas Houlihan, executive director of the WPVGA. “We enjoy a strong partnership with CALS researchers in an ongoing effort to solve problems and improve crops, all with the goal of enhancing the economic vitality of Wisconsin farmers.”

Over the decades, multi-disciplinary teams of CALS experts have coalesced around certain crops, including potato, pooling their expertise.

“Once you get this kind of core group working, it allows you to do really high-impact work,” notes Patty McManus, professor and chair of the Department of Plant Pathology and a UW–Extension fruit crops specialist.

CALS’ prowess in potato, for instance, helped the college land a five-year, $7.6 million grant from the U.S. Department of Agriculture to help reduce levels of acrylamide, a potential carcinogen, in French fries and potato chips. The multistate project involves plant breeders developing new lines of potato that contain lower amounts of reducing sugars (glucose and fructose) and asparagine, which combine to form acrylamide when potatoes are fried. More than a handful of conventionally bred, low-acrylamide potato varieties are expected to be ready for commercial evaluations within a couple of growing seasons.

“It’s a national effort,” says project manager Paul Bethke, associate professor of horticulture and USDA-ARS plant physiologist. “And by its nature, there’s a lot of cross-talk between the scientists and the industry.”

Working with industry and other partners, CALS researchers are responding to other emerging trends, including the growing interest in sustainable agricultural systems.

“Maybe 50 years ago, people focused solely on yield, but that’s not the way people think anymore. Our crop production people cannot just think about crop production, they have to think about agroecology, about sustainability,” notes Tracy. “Every faculty member doing production research in the agronomy department, I believe, has done some kind of organic research at one time or another.”

Embracing this new focus, over the past two years CALS has hired two new assistant professors—Erin Silva, in plant pathology, who has responsibilities in organic agriculture, and Julie Dawson, in horticulture, who specializes in urban and regional food systems.

“We still have strong partnerships with the commodity groups, the cranberries, the potatoes, but we’ve also started serving a new clientele—the people in urban agriculture and organics that weren’t on the scene for us 30 years ago,” says Goldman. “So we have a lot of longtime partners, and then some new ones, too.”

Working alongside their applied colleagues, the college’s basic plant scientists have engaged in parallel efforts to reveal fundamental truths about plant biology—truths that often underpin future advances on the applied side of things.

For example, a team led by Aurélie Rakotondrafara, an assistant professor of plant pathology, recently found a genetic element—a stretch of genetic code—in an RNA-based plant virus that has a very useful property. The element, known as an internal ribosome entry site, or IRES, functions like a “landing pad” for the type of cellular machine that turns genes—once they’ve been encoded in RNA—into proteins. (A Biology 101 refresher: DNA—>RNA—>Protein.)

This viral element, when harnessed as a tool of biotechnology, has the power to transform the way scientists do their work, allowing them to bypass a longstanding roadblock faced by plant researchers.

“Under the traditional mechanism of translation, one RNA codes for one protein,” explains Rakotondrafara. “With this IRES, however, we will be able to express several proteins at once from the same RNA.”

Rakotondrafara’s discovery, which won an Innovation Award from the Wisconsin Alumni Research Foundation (WARF) this past fall and is in the process of being patented, opens new doors for basic researchers, and it could also be a boon for biotech companies that want to produce biopharmaceuticals, including multicomponent drug cocktails, from plants.

Already, Rakotondrafara is working with Madison-based PhylloTech LLC to see if her new IRES can improve the company’s tobacco plant-based biofarming system.

“The idea is to produce the proteins we need from plants,” says Jennifer Gottwald, a technology officer at WARF. “There hasn’t been a good way to do this before, and Rakotondrafara’s discovery could actually get this over the hump and make it work.”

While Rakotondrafara is a basic scientist whose research happened to yield a powerful application, CALS has a growing number of scientists—including those involved in the corn phenotyping project—who are working at the exciting new interface where basic and applied research overlap. This new space, created through the mind-boggling advances in genomics, informatics and computation made in recent years, is home to an emerging scientific field where genetic information and other forms of “big data” will soon be used to guide in-the-field plant-breeding efforts.

Sequencing the genome of an organism, for instance, “is almost trivial in both cost and difficulty now,” notes agronomy’s Bill Tracy. But a genome—or even a set of 1,000 genomes—is only so helpful.

What plant scientists and farmers want is the ability to link the genetic information inside different corn varieties—that is, the activity of specific genes inside various corn plants—to particular plant traits observed in the greenhouse or the field. The work of chronicling these traits, known as phenotyping, is complex because plants behave differently in different environments—for instance, growing taller in some regions and shorter in others.

“That’s one of the things that the de Leon and Kaeppler labs are now moving their focus to—massive phenotyping. They’ve been doing it for a while, but they’re really ramping up now,” says Tracy, referring to agronomy faculty members Natalia de Leon MS’00 PhD’02 and Shawn Kaeppler.

After receiving a large grant from the Great Lakes Bioenergy Research Center in 2007, de Leon and Kaeppler decided to integrate their two research programs. They haven’t looked back. With de Leon’s more applied background in plant breeding and field evaluation, plus quantitative genetics, and with Kaeppler’s more basic corn genetics expertise, the two complement each other well. The duo have had great success securing funding for their various projects from agencies including the National Science Foundation, the U.S. Department of Agriculture and the U.S. Department of Energy.

“A lot of our focus has been on biofuel traits, but we measure other types of economically valuable traits as well, such as yield, drought tolerance, cold tolerance and others,” says Kaeppler. Part of the work involves collaborating with bioinformatics experts to develop advanced imaging technologies to quantify plant traits, projects that can involve assessing hundreds of plants at a time using tools such as lasers, drone-mounted cameras and hyperspectral cameras.

This work requires a lot of space to grow and evaluate plants, including greenhouse space with reliable climate control in which scientists can precisely measure the effects of environmental conditions on plant growth. That space, however, is in short supply on campus.

“A number of our researchers have multimillion-dollar grants that require thousands of plants to be grown, and we don’t always have the capacity for it,” says Goldman.

That’s because the Walnut Street Greenhouses, the main research greenhouses on campus, are already packed to the gills with potato plants, corn plants, cranberries, cucumbers, beans, alfalfa and dozens of other plant types. At any given moment, the facility has around 120 research projects under way, led by 50 or so different faculty members from across campus.

Another bottleneck is that half of the greenhouse space at Walnut Street is old and sorely outdated. The facility’s newer greenhouses, built in 2005, feature automated climate control, with overlapping systems of fans, vents, air conditioners and heaters that help maintain a pre-set temperature. The older houses, constructed of single-pane glass, date back to the early 1960s and present a number of challenges to run and maintain. Some don’t even have air conditioning—the existing electrical system can’t handle it. Temperatures in those houses can spike to more than 100 degrees during the summer.

“Most researchers need to keep their plants under fairly specific and constant conditions,” notes horticultural technician Deena Patterson. “So the new section greenhouse space is in much higher demand, as it provides the reliability that good research requires.”

To help ameliorate the situation, the college is gearing up to demolish the old structures and expand the newer structure, adding five more wings of greenhouse rooms, just slightly north of the current location—out from under the shadow of the cooling tower of the West Campus Co-Generation Facility power plant, which went online in 2005. The project, which will be funded through a combination of state and private money, is one of the university’s top building priorities.

Fortunately, despite the existing limitations, the college’s plant sciences research enterprise continues apace. Kaeppler and de Leon, for example, are involved in an exciting phenotyping project known as Genomes to Fields, which is being championed by corn grower groups around the nation. These same groups helped jump-start an earlier federal effort to sequence the genomes of many important plants, including corn.

“Now they’re pushing for the next step, which is taking that sequence and turning it into products,” says Kaeppler. “They are providing initial funding to try to grow Genomes to Fields into a big, federally funded initiative, similar to the sequencing project.”

It’s a massive undertaking. Over 1,000 different varieties of corn are being grown and evaluated in 22 environments across 13 states and one Canadian province. Scientists from more than a dozen institutions are involved, gathering traditional information about yield, plant height and flowering times, as well as more complex phenotypic information generated through advanced imaging technologies. To this mountain of data, they add each corn plant’s unique genetic sequence.

“You take all of this data and just run millions and billions of associations for all of these different traits and genotypes,” says de Leon, who is a co-principal investigator on the project. “Then you start needing supercomputers.”

Once all of the dots are connected—when scientists understand how each individual gene impacts plant growth under various environmental conditions—the process of plant breeding will enter a new sphere.

“The idea is that instead of having to wait for a corn plant to grow for five months to measure a certain trait out in the field, we can now take DNA from the leaves of little corn seedlings, genotype them and make decisions within a couple of weeks regarding which ones to advance and which to discard,” says de Leon. “The challenge now is how to be able to make those types of predictions across many environments, including some that we have never measured before.”

To get to that point, notes de Leon, a lot more phenotypic information still needs to be collected—including hundreds and perhaps thousands more images of corn ears and cobs taken using flatbed scanners.

“Our enhanced understanding of how all of these traits are genetically controlled under variable environmental conditions allows us to continue to increase the efficiency of plant improvement to help meet the feed, food and fiber needs of the world’s growing population,” she says.

Sidebar:

The Bigger Picture

Crop breeders aren’t the only scientists doing large-scale phenotyping work. Ecologists, too, are increasingly using that approach to identify the genetic factors that impact the lives of plants, as well as shape the effects of plants on their natural surroundings.

“Scientists are starting to look at how particular genes in dominant organisms in an environment—often trees—eventually shape how the ecosystem functions,” says entomology professor Rick Lindroth, who also serves as CALS’ associate dean for research. “Certain key genes are driving many fantastically interesting and important community- and ecosystem-level interactions.”

How can tree genes have such broad impacts? Scientists are discovering that the answer, in many cases, lies in plant chemistry.
“A tree’s chemical composition, which is largely determined by its genes, affects the community of insects that live on it, and also the birds that visit to eat the insects,” explains Lindroth. “Similarly, chemicals in a tree’s leaves affect the quality of the leaf litter on the ground below it, impacting nutrient cycling and nitrogen availability in nearby soils.”

A number of years ago Lindroth’s team embarked on a long-term “genes-to-ecosystems” project (as these kinds of studies are called) involving aspen trees. They scoured the Wisconsin landscape, collecting root samples from 500 different aspens. From each sample, they propagated three or four baby trees, and then in 2010 planted all 1,800 saplings in a so-called “common garden” at the CALS-based Arlington Agricultural Research Station.

“The way a common garden works is, you put many genetic strains of a single species in a similar environment. If phenotypic differences are expressed within the group, then the likelihood is that those differences are due to their genetics, not the environment,” explains Lindroth.

Now that the trees have had some time to grow, Lindroth’s team has started gathering data about each tree—information such as bud break, bud set, tree size, leaf shape, leaf chemistry, numbers and types of bugs on the trees, and more.

Lindroth and his partners will soon have access to the genetic sequence of all 500 aspen genetic types. Graduate student Hilary Bultman and postdoctoral researcher Jennifer Riehl will do the advanced statistical analysis involved—number crunching that will reveal which genes underlie the phenotypic differences they see.

In this and in other projects, Lindroth has called upon the expertise of colleagues across campus, developing strategic collaborations as needed. That’s easy to do at UW–Madison, notes Lindroth, where there are world-class plant scientists working across the full spectrum of the natural resources field—from tree physiology to carbon cycling to climate change.

“That’s the beauty of being at a place like Wisconsin,” Lindroth says.

Want to help? The college welcomes your gift toward modernizing the Walnut Street Greenhouses. To donate, please visit: supportuw.org/giveto/WalnutGreenhouse. We thank you for your contribution.
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Cash Crop Biomass

WISCONSIN FARMERS have been growing biomass for generations, says Kevin Shinners. They just have a different name for it.

“Biomass is really just poor-quality forage,” says the CALS agricultural engineer. “We allow it to get very mature and it’s really high in fiber, so it doesn’t make very good animal feed, but it
makes great biomass.”

And Wisconsin farmers have a leg up in the business of producing biomass, says Shinners, a specialist in forage systems who branched out into bioenergy crops about 10 years ago.

“We have all of the tools to harvest and handle and process it. And an added advantage is that when we take biomass off the field, we have new places to put our dairy manure,” he says. “When you take corn stover off the field, you’re
removing nutrients that you need for next year’s crop. A Wisconsin farmer can apply manure, while an Illinois farmer may have to go out and buy fertilizer.”

Wisconsin also is rich in off-farm resources. The state’s custom harvesters are expert at chopping stalks and grass, and biomass could fit nicely into their schedule. After they finish chopping corn silage in September, crews could move on to corn stover or switchgrass in October and November, spreading fixed costs over more acres and keeping employees working longer.

In fact, under some business models, farmers might job out most of their biomass crop production. If the crop is a perennial, such as switchgrass, the farmer may spend more time in front of the computer and on the phone than out in the field. “Once the crop is established, he’ll manage fertilization and weed control through an agronomic service, cutting and removal through a custom harvester and marketing through a biomass aggregator,” Shinners says.

But even though Wisconsin farmers may be very much at home with the types of crops involved and the mechanics of producing them, they’ll be on less familiar ground when it comes to marketing, Shinners notes.

“If you’re a cash crop farmer, you’re used to marketing your corn and beans through multiple paths, selling some out of the field, storing some, selling futures, to optimize what you earn on an annual basis,” he says. “For biomass, you’ll have to change your mindset.

“If a firm builds a large cellulosic biorefinery here, it will need an absolute dedicated supply,” Shinners says. “If half the people in the area decided not to produce biomass one year, that plant would be a dinosaur.” Meaning that a critical mass of local farmers must be willing to lock into a long-term production contract.

The economics of biomass are driven by the fact that, pound for pound, the stuff isn’t worth as much as other crops. Profit margins may be slim, so farmers will need to produce as efficiently as possible.

That’s where Shinners comes in. His research centers on streamlining the harvest and handling a variety of biomass crops, including such perennials as switchgrass and reed canarygrass, and annuals such as sorghum. But his biggest push has been in corn stover—the stalks and leaves and cobs left when the kernels are removed—simply because there’s so much of it.

“There are some 90 million acres of corn being grown in the United States this year, and with the prices we’re seeing, there’s going to be more and more of it grown. If you’re really interested in biomass, it’s right there at our doorstep,” he reasons.

Since profit-minded crop producers aim to make as few trips across the field as possible, Shinners’ first efforts focused on harvesting both corn grain and corn stover in one pass. Essentially, he grafted a forage harvester to the back of a combine and hitched a wagon behind to catch the chopped stover.

This impressive 50-foot train of machinery worked, he says, but handling two crops at the same time slowed down the grain harvest, putting both yield and quality at risk. “That’s even more of an issue these days, when we have seen corn go over $7 per bushel,” he says. “As corn grain increases in value, everything that slows the combine down has a much greater economic cost.”

Shinners is focusing now on a system in which the combine harvests grain and leaves the stover behind in a long, neat row. “A custom harvester could come in behind and chop these windrows and store them for the farmer.”

Since buyers will need year-round deliveries, storing biomass crop until it’s needed is part of the equation. Shinners thinks the best approach is one that dairy farmers use for forage—seal it from the air in long plastic bags or covered bunkers and let it ferment. “We know this from dairying: You can open up a silo bag from two years ago and it’s still good quality,” he says.

That fermented biomass could be good enough to eat—by livestock, at least—which may offer farmers a way to take advantage of the bioenergy market without having to wait for a biomass refinery to be built nearby.

“If we apply amendments like lime right before we store corn stover, the feed value can increase substantially,” says Shinners. “So instead of waiting for somebody to develop a biorefinery in Wisconsin to convert stover to ethanol, why not divert some of the grain normally used to feed cattle toward ethanol production and use the stover to replace the corn as animal feed?”

Corn's Wow Factor

Bill Tracy knew it was coming. But the burst of sweetness from the ear of corn he’d just bitten into was so swift that he could offer just one word of critique: “Wow!”

That’s a common reaction to the new hybrid developed by Tracy’s breeding program. Nicknamed Wow corn, its kernels pack a sweet wallop without sacrificing deeper flavors, making it a potentially attractive option for fresh-market growers.

“We’re very excited about this corn,” says Tracy. “It’s a combination of naturally occurring genes that has never existed before, and it results in a very nice flavor. Literally every person who has ever bitten into it, the first thing they say is, ‘Wow!’”

As director of one of the country’s only sweet-corn breeding programs, Tracy continues to look for ways to improve the popular staple, grown on around 80,000 acres in Wisconsin each year. The new variety, first evaluated in 2008, could be released to growers within two or three years.

Grain of Doubt

LIKE A SWARM OF FIREFLIES, a group of teenagers creates a chaotic dance of flashlight beams as they scatter down a path leading into Don Schuster’s corn. Within moments, they are gone, swallowed by the deepening blackness of the tall corn and the encroaching fall evening. Only their voices drift back to us, standing on the periphery of the nine-acre field. Others, too—the excited peal of children and young couples who have come to wander the serpentine paths Schuster has carved into his corn. Their laughter floats above us like the whispers of ghosts, happily lost in this maze of maize.

The real trouble with corn may not be what it does wrong, but what it does right.

Strange phenomena, corn mazes. Schuster BS’86 MS’94 has been creating them for nine years on his farm near Deerfield, Wis., and he’s still uneasy about tearing up good corn to make a human-sized rat race. “It goes against everything I was brought up to think about a cornfield,” he says. But as a part-time economist with CALS’ Center for Integrated Agricultural Systems, he also understands the bottom line. In a good year, 11,000 people will pay two to six dollars each to get lost in his family’s field, enough to make whatever money he gets from the corn itself incidental.

This would have seemed a bizarre reality to Schuster’s ancestors, who farmed corn for four generations before him. But if those men could walk through Don Schuster’s field today, they would be lost for a different reason. The plants that towered around them would look alien, hardly resembling any cornfield they would have known.

Seventy years ago, Schuster’s grandfather might have planted 8,000 corn seeds per acre, leaving plenty of room for the stalks to spread out. Today, most farmers put in 30,000. Schuster goes beyond that: To enhance the closed-in feel of his maze, he plants rows in both directions, packing 44,000 stalks into each acre. By August, his corn forms an eight-foot-tall wall with a canopy so thick that sunlight hardly reaches the ground.

“That’s a lot of what makes people enjoy the maze,” says Schuster. “You get in there and you can’t see over the corn. It’s like a big tunnel.” But it’s an effect created not by light or darkness or by Schuster’s zero-turn-radius mower. It owes its magic to the plant itself, and the human conquest of it. We have made corn a jungle.

Through 7,000 years of farming, humans have turned a wild grass that grew in the valleys of Central America into Zea mays, one of the most bountiful food crops in existence. Today, corn grows on every continent except Antarctica, from the American heartland to the northern plains of China to the Andes mountains. Worldwide, farmers harvest some 700 million metric tons of its kernels each year, making it the second-largest food crop on the planet, behind sugarcane.

Ample credit for that dominance goes to the generations of farmers and breeders who have tailored the genetic superiority of the corn plant. Like a thoroughbred race horse, modern corn is a rare beast, designed to perform. It has been honed to grow taller and healthier and live closer to its neighbors, traits that have driven per-acre corn yields to historic levels. While 80 years ago American farmers yielded about 26 bushels of corn from one acre, now they often haul in more than 200.

Although corn occupies about 20 percent less land now than it did before World War II, our nation’s annual corn harvest has more than quintupled. Last year, farmers harvested a record-busting 13.1 billion bushels of corn—enough to supply every man, woman and child in the country with a six-and-a-half pound box of kernels every day for an entire year.

Of course we don’t eat all of that corn, at least not as kernels. Only about 12 percent of the U.S. corn crop goes directly into food production; the rest is fed to animals, turned into products such as ethanol or exported. But corn finds its way back to us in many ways—as sweeteners like high fructose corn syrup and dextrose, as starches in baked goods and confectionaries, as cooking oils and margarine, and as proteins and enzymes added to hundreds of foods. More than one quarter of the items on supermarket shelves now contain some form of corn, from Twinkies to fruit juice, from waffles to salad dressing, from soup to nut bread. Order a typical fast-food meal and you’re eating corn in every bite: Corn feeds the cattle that make the beef; corn enriches the bread in the bun; corn sweetens the soda and bathes the French fries to golden perfection. It’s even in the ketchup.

And therein lies the problem. As much as we have ruled corn, corn now rules us. It’s in our T-shirts and boxer shorts and our children’s disposable diapers. It’s in our vitamins and our prescription drugs. It’s in lipstick. It’s in soap. Corn starch is in the finish applied to these magazine pages, the cardboard boxes they were shipped in and the gasoline tanks of the vans that delivered them. Our daily lives have come to rely so heavily on corn that 13.1 billion bushels of it seems hardly enough. Increased demand for corn, especially from foreign markets and the ethanol industry, has pushed corn prices to historic highs, more than tripling in the past two years. After summer floods in Iowa and Wisconsin raised fears of a poor harvest, corn spiked to near $8 a bushel, a level never before seen.

With corn now blanketing a swath of U.S. soil that could cover half of Texas, planting more hardly seems appealing. Nitrogen and phosphorus runoff from cornfields in the Mississippi River basin is contributing to a growing dead zone in the Gulf of Mexico, where excess nutrients cause oxygen levels to drop and make water inhabitable for fish. Growing more corn would exacerbate those problems, especially since most of the lands best suited for corn are already planted with it. If farmers choose to till highly erodable grasslands for corn, soil erosion and runoff problems are bound to get worse.