Sweeping Our Soil Away

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Soil scientist Gyles Randall calls it the “broom handle” effect. That’s when a corn field has been shaved clean: stalks, leaves, the whole nine yards — all the way to the stubble, leaving a field with a sparse, bristly look. There’s a whole lot of bare soil between those broom handles, and not much organic matter. “That scares the bejeebers out of me,” Randall, who regularly monitors cropland erosion and fertilizer runoff in southern Minnesota, told me recently. Crew-cut cornfields are just one possible response to an inescapable fact: we simply cannot raise enough corn in this country to meet our seemingly insatiable thirst for fuel.More...

But agriculture, ever the eager overachiever, is giving it a try as the ethanol boom hits full stride. Estimates of just how much corn will be raised for ethanol in the future vary, but all trends point up. According to Purdue University agricultural economist Chris Hurt, this year the demand for ethanol will surge from the current 7.3 billion gallons to 13.5 billion gallons. On Feb. 22, the USDA released a grains and oilseeds outlook for 2008 that predicts corn use for ethanol production will increase this year by 900 million bushels — a 28 percent jump from 2007. Even if 90 million acres of corn is planted this spring — The USDA’s latest forecast calls for 86 million acres in 2008 — there are doubts as to whether it will be enough to supply the capacity of current ethanol plants.

A recent U.S. Senate proposal recommended the production of 15 billion to 36 billion gallons of biofuels by 2022. If a major portion of that fuel comes from corn ethanol, the long-term demand for corn will be unprecedented.

Because of the biofuels boom and increased worldwide demand for all agricultural products, cropland is becoming a dear resource. Overall, corn, soybeans and wheat acreage is expected to be 225 million acres in 2008, 7.4 million acres more than was planted in 2007, according to the USDA.

Where will that land come from? According to the USDA’s experts, some it will come at the cost of cotton ground and the 2.5 million acres of Conservation Reserve Program (CRP) setaside land that is coming out of contract this year. Some farmers have placed newspaper ads encouraging landowners to rent land for crops, rather than renew CRP contracts. Recently, the New York Times and USA Today have provided grim details on just how expendable CRP acres and other land growing perennial plants have become as the demand for cropland explodes. As Time‘s “The Clean Energy Scam” article pointed out last month, ethanol’s land grab is extending as far away as the Amazon.

The rest of it?

One guess is that forage and grassland will be plowed up for corn. The result, say farmers, soil scientists and environmental experts, could be increased erosion, more contaminated water and less wildlife habitat. “We’re concerned about ethanol if it’s going to take grassland out and put it into production,” Matt Holland, director of conservation programs for Pheasants Forever in Minnesota, told me.

In February, the scientific journal Science published two papers that concluded biofuels could make the environment worse by pushing farmers worldwide to plow up grasslands and clear forests for bioenergy. One paper concluded that when changes in land use are taken into account, corn-based ethanol could nearly double greenhouse gas emissions over a 30-year period.

Soil scientists and conservation groups aren’t the only ones that fear the environmental impacts of corn-based biofuels. Of the more than 1,000 farmers who responded to the 2007 Iowa Farm and Rural Life Poll, 75 percent said removing corn residue for ethanol will increase soil erosion. Even as they expressed optimism that biofuels will be an economic boon, 77 percent said bringing marginal land into grain production would reduce wildlife habitat.

Corn ethanol boosters say one way farmers can meet biofuel demand is not by using more land but by increasing how much corn current fields produce. Indeed, corn hybrids are getting better and better. Walk into any farm country coffee shop and you will hear farmers express wonder at how well new corn varieties weather drought and disease. The USDA projects average corn yields in the U.S. will rise from 155 to 173 bushels per acre by 2018. But there are concerns some of that yield increase is coming not from individual corn plants, but from stretching the boundaries of what is considered arable.

“Fields have become larger,” says northeast Iowa farmer Dan Specht. “The edges are getting cleaned up and fencerows are being cleared. The bulldozer operators have definitely been busy. People are farming roads right to the bottom of the ditch, farming right around the telephone poles, getting two more rows where a fenceline used to be.”

Making use of every square foot may be efficient, but it doesn’t leave much room for fencerows, grassy waterways and other structures that provide wildlife habitat while protecting soil and water.

USDA’s dreary forecast
Perhaps the most extensive analysis of the possible farm-level environmental impacts of biofuels came in 2007 from the USDA’s Economic Research Service (ERS) and its Office of the Chief Economist. That analysis concluded that as corn production for biofuels increases, nitrogen fertilizer use will go up around 6 percent by 2016 in both the Corn Belt (Iowa, Illinois, Indiana and Ohio) and Lake States (Minnesota, Wisconsin and Michigan), and pesticide use will be almost 5 percent higher. The amount of nitrogen leaching into groundwater will be 2.4 percent higher in the Corn Belt by 2016, and 10.6 percent higher in the Lake States. Erosion will be between 1.5 and 3 percent higher during the next decade.

Nitrogen fertilizer runoff from Midwestern farms is the major cause of the Gulf of Mexico’s oxygen-depleted “Dead Zone.” Scientists have estimated that nitrogen levels in the Mississippi River basin will need to decrease by 30 percent to 50 percent to shrink this hypoxic area. But the increase in corn cultivation required to produce 15 billion gallons of ethanol by 2022 would increase the amount of nitrogen in the Gulf by at least 10 percent, according to a study published in the Proceedings of the National Academy of Sciences in March.

Broom & doom
As Randall points out, one potential contributor to increased erosion and chemical runoff is taking the next step beyond making ethanol from the corn kernel and using the entire stalk or “residue” of the corn plant for fuel via cellulosic technology. This technology is still not commercially viable, but it’s generating a lot of excitement. Besides making biofuel from the corn stalk, engineers say we could also burn it as biomass for ethanol plants that are suffering from high natural gas prices.

Corn stalks are often dismissed as crop waste, but in fact they play a critical role in soil conservation. They protect it from the erosive force of rain drops and are key to replacing organic matter. The importance of crop residue is one reason most farmers have given up the moldboard plow, which buries such material.

But crop residues will play a bigger part in biofuels in the future, according to government analyses. One study by the U.S. Department of Energy and the USDA estimates that crop residues will provide one-third of the ethanol industry’s needs by the middle of the 21st century. Fulfilling such a role would require 60 percent to 75 percent of crop residue to be recovered, according to the USDA.

Some residue can be removed without causing major environmental problems, but it’s not clear where the tipping point is. Randall, for one, believes that taking more than half the residue may be detrimental. Others say — depending on the slope of the land and the soil’s organic matter content — as much as two-thirds could be sacrificed without major problems. The bottom line is we don’t have a handle on exactly how much residue should be left on a field to protect the soil and keep it agronomically viable.

“Despite the broad recognition of the need for specific guidelines for residue removal to avoid environmental degradation, none yet exist,” concluded the USDA in a 2006 report.

During the past few decades, the conventional wisdom has been that farmers needed to rotate corn with another crop from year-to-year in order to fight disease, preserve soil fertility and maintain decent yields. Rotations are seen as a way of reducing fertilizer use while naturally breaking up pest cycles. Planting soybeans or alfalfa between corn crops can fix nitrogen in the soil. Small grains such as rye protect the soil while naturally controlling weeds. When it’s continuous corn, such natural defenses are supplanted with tillage and chemicals.

The biofuels craze has ushered in an era when “corn-on-corn” is agronomically acceptable. The ERS-Office of the Chief Economist analysis predicts that continuous corn plantings will rise 28 percent by 2016 in the Corn Belt and 39 percent in the Lake States. Farm magazines and Extension bulletins are now full of advice on how to raise corn on the same field year-after-year. Yes, yields will take a hit in the short term, but agrichemicals and tillage offer a way to compensate, say the experts.

Progressive Farmer magazine recently described how one southeast Minnesota operation went from 2,900 acres of corn to almost 4,500 acres on a total of 6,000 acres; the farm has three ethanol plants within 30 miles. The magazine’s advice? Pour on more fertilizer and get rid of plant residue.

In recent years, soybeans have been the most popular crop used as a rotation between corn plantings. Some soil scientists aren’t that crazy about soybeans as a rotation crop, since they can burn up organic matter and don’t add that much plant residue back to the soil. In a way, soil scientist Randall says, corn-on-corn can be a plus for the soil compared to corn-soybeans. But he has a big caveat.

“As long as we practice good conservation” corn-on-corn is okay, he says. “We need to not be moldboard plowing.”

But conventional tillage in the Corn Belt will go up as much as 2.8 percent by 2016, according to the USDA. Although there is a fair amount of conservation tillage done to raise soybeans, interest in corn conservation tillage has plateaued. Soil scientists say that cover crops — crops such as rye planted after the harvest of corn to protect the soil and build organic matter — should play an increasingly important role in crop rotations if we are to balance production with conservation. But cover crop use in the Corn Belt is quite low, says a study published in the Sept./Oct. 2007 edition of the Journal of Soil and Water Conservation. Only 11 percent of the more than 1,000 farmers surveyed in Iowa, Illinois, Indiana and Minnesota had planted cover crops sometime during the previous five years, according to the study.

Looking at such trends, it’s clear using a row crop like corn as the basis for biofuels is ultimately not a good long-term strategy environmentally or agronomically. Perennial plant systems such as grass offer a better alternative down the road. But that means sharing some of the research and development resources corn hybrids have soaked up for so long.

“For example, we’re probably looking at switchgrass genetics that are equivalent to 1940s corn genetics,” Randall says. “I’d like to think we could pump public research dollars into faster growing, perennial plant systems.”

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