It may be more cost-effective, energy-efficient and environmentally sustainable to use corn stover for generating an energy-rich oil called bio-oil and for making biochar to enrich soils and sequester carbon than to turn it into cellulosic ethanol, according to a new study from ARS. Photo courtesy of Courtesy of DOE/NREL.

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Sustainable Corn Production Supports Advanced Biofuel Feedstocks

By Ann Perry
November 24, 2009

Researchers worldwide are trying to economically convert cellulosic biomass such as corn stover into "cellulosic ethanol." But Agricultural Research Service (ARS) scientists have found that it might be more cost-effective, energy-efficient and environmentally sustainable to use corn stover for generating an energy-rich oil called bio-oil and for making biochar to enrich soils and sequester carbon.

Stover is made up of the leaves, husks, cobs and stalks of the corn plant, and could provide an abundant source of feedstock for cellulosic ethanol production after the grain is harvested. But removing stover from the field would leave soil more vulnerable to erosion, deplete plant nutrients and accelerate the loss of soil organic matter.

Several ARS scientists collaborated with the National Corn Growers Association to explore other options for using corn stover as biofuel feedstock. Chemical engineer Akwasi Boateng, chemist Charles Mullen, mechanical engineer Neil Goldberg and research leader Kevin Hicks all work at the ARS Eastern Regional Research Center in Wyndmoor, Pa. Chemist Isabel Lima, who works at the ARS Southern Regional Research Center in New Orleans, La.; and soil scientist David Laird, who works at the ARS National Laboratory for Agriculture and the Environment in Ames, Iowa, also contributed to the study.

The team used fast pyrolysis, which is rapid heating in the absence of oxygen, to transform corn stover and cobs into bio-oil and bio-char. They found that the bio-oil captured 70 percent of the total energy input, and the energy density of the bio-oil was five to 16 times the energy density of the feedstock.

This suggests it could be more cost-effective to produce bio-oil through a distributed network of small pyrolyzers and then transport the crude bio-oil to central refining plants to make "green gasoline," rather than transporting bulky stover to a large centralized cellulosic ethanol plant.

In addition, about 18 percent of the feedstock was converted into bio-char, which contains most of the mineral nutrients in the corn residues. Using biochar as a soil amendment would return those nutrients to the soil, reduce leaching of other nutrients, help build soil organic matter and sequester carbon. These benefits would help mitigate the adverse environmental effects of harvesting stover for fuel production.

These findings were published online in the journal Biomass and Bioenergy.

This research supports the U.S. Department of Agriculture (USDA) priority of developing new sources of bioenergy. ARS is USDA's principal intramural scientific research agency.

Mild dehydration appears to affect mood and cognitive ability of young athletes in addition to impacting physical performance, according to a new ARS study. Click the image for more information about it.

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Dehydration Affects Mood, Not Just Motor Skills

By Rosalie Marion Bliss
November 23, 2009

Dehydration has long been known to compromise physical performance. Now, a new study provides insight into the effects of mild dehydration on young athletes, and possibly into the lives of people too busy to consume enough water daily. The study was supported in part by the Agricultural Research Service (ARS) and a U.S. Army grant.

Biological psychologist Kristen D’Anci led the study while with the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston, Mass. Other coauthors were Holly Taylor with Boston-based Tufts University, and Caroline Mahoney with the U.S. Army Natick Soldier Systems Center in Natick, Mass.

The study adds to a relatively new area of research and was published recently in Perceptual and Motor Skills.

Athletes commonly lose between 2 and 4 percent of their body weight during athletic practice. The researchers wanted to explore the effects of dehydration on cognition—the ability to use information to function—and mood.

About 30 male and female Tufts University students, with an average age of 20, participated in the study. When students were assigned to the “dehydration group,” they were not given fluids during athletics. When in the control condition, they were given water throughout athletics.

The participants weighed in before and after athletics to assess body water loss. After athletic activity, participants underwent cognitive tests, which included short-term memory and mood scales among others. The researchers found that dehydration was associated with negative mood, including fatigue and confusion, compared to the hydrated group.

The level of mild dehydration (losses of between 1 percent and 2 percent) experienced among participants in the study could be compared to the mild dehydration some people experience in their daily lives from drinking insufficient amounts of water, according to authors.

ARS is the principal intramural scientific research agency of the U.S. Department of Agriculture (USDA). This research supports the USDA priority of improving nutrition and health.

Read the magazine story to find out more.

ARS researchers have been studying plant reactions to changes in C02 levels, from the Ice Age—13,000 to 18,000 B.C.—to the year 2050 A.D. by growing them in long, plastic-covered "time tunnels."

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Time-Tunneling for Climate Change Clues

By Don Comis
November 20, 2009

If you look closely at individual plant species' responses in the past, you may find that the largest effects of high carbon dioxide (CO₂) levels occurred decades ago, according to Agricultural Research Service (ARS) scientists. That is when the botanical structure of the world's grasslands changed dramatically, offering clues to the future.

For several years, Wayne Polley and Philip Fay, ecologists at the ARS Grassland Soil and Water Research Laboratory in Temple, Texas, have been studying plant reactions to a gradient of CO₂ levels, from the Ice Age—13,000 to 18,000 B.C.—to the year 2050 A.D. Their research supports the U.S. Department of Agriculture's priority of developing long-range global change strategies.

The ecologists do their research with "time tunnels." These are long, plastic-covered tunnels in which tall prairie grasses are exposed to increasing levels of CO₂. These tunnels are an alternative to traditional open-top outdoor chambers in which plants are exposed to only one level of CO₂ per chamber.

Among their recent findings is that grasses respond to higher CO₂ levels by using water more efficiently. They have been measuring plant water use for four years now, ever since they modified the tunnels by placing them over steel-lined, soil-filled pits with soil-weighing lysimeters to measure soil water loss.

More efficient water use by prairie grasses sounds like a good thing, but weedy shrubs and grasses also benefit from increased water use efficiency. This may help weeds outcompete desirable forage plants. But the cumulative effects of these individual species' responses on plant communities won't be obvious for years.

Read more about this and other climate change research in the November/December 2009 issue of Agricultural Research magazine.

ARS is USDA’s principal intramural scientific research agency.

ARS computational biologist Doreen Ware and colleagues have completed a four-year effort to sequence the genome of corn. Click the image for more information about it.

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USDA Scientists, Colleagues Sequence Corn Genome

By Dennis O'Brien
November 19, 2009

WASHINGTON, November 19, 2009—U.S. Department of Agriculture (USDA) scientists and their colleagues have completed a four-year effort to sequence the genome of corn, an achievement expected to speed up development of corn varieties that will help feed the world and meet growing demands for using this important grain crop as a biofuel and animal feed. The results represent the largest and most complex plant genome sequenced to date, and are the cover story in the November 20 issue of the journal Science.

"Sequencing the corn genome will help researchers in the United States and around the world develop corn varieties to confront critical global challenges like climate change, hunger, and renewable energy," said Edward B. Knipling, administrator of USDA's Agricultural Research Service (ARS), USDA's principal intramural scientific research agency. "This effort will provide scientists a preliminary blueprint for identifying genetic pathways that will lead to a better understanding of corn and enable scientists to improve corn in a number of ways."

The sequencing will help researchers uncover the relationships between corn genes and traits, develop an overall picture of the plant's genetic makeup, and broaden understanding of how the complex interplay of genetics and environment determines the plant's health and viability. The work also is expected to lead to development of corn varieties with higher yields and better tolerance of droughts, pests and diseases. It also should help scientists produce varieties with fibers, stalks and cellular structures that will make corn a better source of biofuel.

The team, which included Doreen Ware, a computational biologist at the ARS Robert W. Holley Center for Agriculture and Health in Ithaca, N.Y., has released the most comprehensive draft sequence to date, providing the most detailed look thus far at the functional portions of the corn genome. Ware led the computational effort and is a lead author of the report along with Richard Wilson of Washington University School of Medicine in St. Louis, Mo., and Patrick S. Schnable of Iowa State University at Ames. Other key participants in the project included the University of Arizona at Tucson and Cold Spring Harbor Laboratory in New York. USDA's National Institute of Food and Agriculture, along with the National Science Foundation and the U.S. Department of Energy, jointly funded the $29.5 million effort.

Edward Buckler, an ARS geneticist at the Holley Center, and Ware also have used next generation sequencing data to assemble a haplotype genetic map of the corn genome that lays out portions of the genome shared by 27 diverse inbred lines of corn. A haplotype is a combination of alleles—alternative forms of genes—that are located closely together on the same chromosome and tend to be inherited together. The corn lines in the haplotype genetic map were selected specifically because they represent the vast majority of the genetic diversity in corn. By searching through these lines, researchers and breeders can unlock corn's genetic potential and significantly accelerate the breeding of plants to meet the demands of the growing world population and the challenges of global climate change. Buckler's "HapMap," which also is published in Science, shows a 30-fold variation in recombination rates, which are the rates that genetic material from parents mix to show up in the progeny. The map is designed to function like the human genome HapMap, making it easier to link genes and genetic patterns with significant traits, Buckler said. The researchers already are linking the HapMap to the basis of hybrid vigor.

Corn, known among scientists as maize, is one of world's most important crops. Corn was a $47 billion crop in the United States last year. It is the largest production crop worldwide, providing not only food for billions of people and livestock, but also critical feedstock for production of biofuels. Ware said the work should serve as a foundation for understanding and improving on other agricultural crops as well. Plants previously sequenced include rice, sorghum, poplar, grape and Arabidopsis thaliana, a plant widely studied as a model organism.

ARS scientists have developed a microwave meter that measures moisture and density of in-shell peanuts faster and easier, both important quality indicators. Image courtesy of Microsoft clipart.

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Microwave Meter Measures Moisture and Density of In-Shell Peanuts

By Sharon Durham
November 19, 2009

A microwave meter that instantaneously measures both moisture and density of in-shell peanuts has been developed by Agricultural Research Service (ARS) scientists, making it easier and faster for producers and processors to determine these important quality indicators.

Moisture content is the most important factor in peanut quality. Kernel moisture content must be less than 10.5 percent, because higher levels can lead to the growth of fungi that produce aflatoxins, which cause illness in animals and humans.

The new apparatus measures density and moisture independently, eliminating an extra testing step and improving an earlier ARS technology that used radio frequencies to determine moisture content.

Using the new technology, peanut graders can determine peanut kernel moisture content with only about 0.5 percent standard error. ARS engineer Samir Trabelsi and retired ARS engineer Stuart O. Nelson, in the ARS Quality and Safety Assessment Research Unit at the agency's Richard B. Russell Agricultural Research Center in Athens, Ga., developed the microwave meter. The method is rapid, nondestructive and eliminates the need for shelling the peanut pods.

In the new process, in-shell peanuts are loaded directly into the sample holder of the microwave meter, and an antenna transmits low-intensity microwaves into the peanut pods. The microwaves pass through the pods and are received by another antenna facing the transmitting antenna. Alterations in the energy level and velocity of the microwaves, as they pass through the pods, reveal moisture content in the kernels and bulk density of the peanut pods. A computer is attached to record moisture and density measurements. For moisture content determination, the new technique also eliminates the need for multiple calibrations and compensates for density and temperature.

The technology has been given a provisional patent and is being tested at five peanut buying stations in Georgia, Alabama and South Carolina.

This research supports the U.S. Department of Agriculture (USDA) priority of ensuring food safety. ARS is USDA's principal intramural scientific research agency.

Nettle moth caterpillar (Darna pallivitta). Click the image for more information about it.

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Invasive Nettle Moth Triggers Hawaii Research

By Marcia Wood
November 18, 2009

Like children everywhere, kids in Hawaii love to run barefoot through tall grass. But an invasive pest called the nettle moth caterpillar can take the fun out of this simple childhood pleasure, according to Agricultural Research Service (ARS) research entomologist Eric B. Jang.

The sharp, spiky hairs of the caterpillar, Darna pallivitta, can cause a painful, stinging sensation. Besides being a hindrance to childhood play, this agricultural pest poses a hazard to people working with palm plants and other commercially grown ornamentals that the insect attacks.

That's why Jang, who’s at the U.S. Pacific Basin Agricultural Research Center in Hilo, Hawaii, is working with colleagues in that state and elsewhere to explore new ways to thwart the insect.

In a highly experimental approach, Jang plans to use sexually sterilized fruit flies, such as sterilized melon flies, as winged carriers of an alluring nettle moth scent, a component of what's known as a pheromone. Sterile melon flies are a logical choice because techniques for producing large numbers of them—to disrupt their normal reproduction and cause their populations to crash—are already in place.

In theory, sterilized melon flies, each carrying a drop of the nettle moth chemical on its back, could be set free in moth-infested locales in Hawaii to quickly and inexpensively distribute the scent wherever they fly. Like decoys, the melon flies would create confusion among amorous male moths that use the scent to find female moths.

Jang and colleagues have described the concept and pheromone component in published scientific articles. ARS and the State of Hawaii Department of Agriculture have provided funding to Jang and co-researchers to pursue this innovative idea, known as "mobile mating disruption."

Former postdoctoral research associate Matthew S. Siderhurst identified and synthesized the nettle moth pheromone compound in early experiments funded by ARS and the Hawaii Invasive Species Council.

The pheromone component can also be placed in traps to detect the caterpillar and monitor its spread, Jang noted.

ARS is the principal intramural scientific research agency of the U.S. Department of Agriculture.

Read the magazine story to find out more.

ARS scientists have found that using alternative types of fertilizers can cut back on greenhouse gas emissions from crop production, at least in one part of the country. Click the image for more information about it.

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Studying Fertilizers to Cut Greenhouse Gases

By Dennis O'Brien
November 17, 2009

Agricultural Research Service (ARS) scientists have found that using alternative types of fertilizers can cut back on greenhouse gas emissions, at least in one part of the country. They are currently examining whether the alternatives offer similar benefits nationwide.

Nitrogen fertilizers are often a necessity for ensuring sufficient crop yields, but their use leads to release of nitrous oxide, a major greenhouse gas, into the atmosphere. Fertilizer use is one reason an estimated 78 percent of the nation's nitrous oxide emissions come from agriculture, according to Ardell Halvorson, a soil scientist at the ARS Soil Plant Nutrient Research Laboratory in Fort Collins, Colo.

Halvorson compared nitrous oxide emissions from corn fields treated with either a conventional nitrogen fertilizer (urea) or either of two specially formulated urea fertilizers—one with "controlled release" polymer-coated pellets, and the other with inhibitors added to "stabilize" the urea to keep more of it in the soil as ammonium for a longer period.

In a two-year experiment at Fort Collins, he collected the emissions using static vented chambers, similar to small "pillbox" structures placed over the soil. He chose a no-till cropping system because it's known to reduce carbon dioxide emissions. He found that the controlled-release fertilizer cut nitrous oxide emissions by a third, and that the stabilized fertilizer cut them almost in half.

Halvorson's results are so far limited to the irrigated fields and cool, semi-arid conditions in and around Fort Collins. But nitrous oxide releases are the result of a complex interplay of conditions that vary from one area to the next, such as soil water content, soil temperatures, soil types, microbial activity, climactic conditions and rainfall patterns. So Halvorson is expanding the study, with support from the fertilizer industry and cooperation of other ARS locations, to see how the fertilizers respond at seven sites around the United States.

The research supports the U.S. Department of Agriculture (USDA) priority of responding to climate change.

Read more about ARS climate change research in the November/December 2009 issue of Agricultural Research magazine.

ARS is USDA's principal intramural scientific research agency.

ARS scientists have found that certain fungi can prevent compounds in grapefruits from interfering with some prescription medicines. Photo courtesy of Florida Department of Citrus.

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Fungi May Hold Key to Reducing Grapefruit Juice Interactions with Medications

By Sharon Durham
November 16, 2009

A fungus may help solve a problem of a grapefruit compound that interacts negatively with certain prescription drugs, according to studies by Agricultural Research Service (ARS) scientists.

Grapefruit contains furanocomarins (FCs), which inhibit the enzymatic activity responsible for metabolizing certain prescribed medications and allowing more of the medication to enter the bloodstream. FCs are phytochemicals commonly found in plants. Two well-known phytochemicals are Vitamins C and E.

Grapefruit juice can interfere with the metabolism of certain medications used to treat a wide range of conditions such as allergies, abnormal heart rhythm, depression, hypertension, infections, heart disease, and high cholesterol. The grapefruit industry may have lost customers who no longer drink grapefruit juice due to their medications.

ARS chemists Kyung Myung and John Manthey and microbiologist Jan Narciso at the ARS Citrus and Subtropical Products Laboratory in Winter Haven, Fla., began the study using a fungus—Aspergillus niger—to bind and break down FCs in grapefruit juice.

Grapefruit juice contains three main FCs. Myung found that A. niger either bound these FCs or enzymatically broke them down into other products. Enzymatic inactivation of these compounds may be a means of eliminating them from commercial grapefruit juice, and work to identify these enzymes in A. niger is in progress. A. niger is one of the most common species of the genus Aspergillus that can cause black mold on certain fruits and vegetables but often doesn’t cause human disease.

Myung and his team decided to also test edible fungi, or mushrooms. In studies, they found that edible mushrooms such as morels, oyster and button mushrooms—when dried, pulverized and added to grapefruit juice—also removed FCs. That provides researchers with evidence that fungal proteins could be responsible for removing the FCs from the grapefruit juice.

This research was published in the Journal of Applied Microbiology and Biotechnology and the Journal of Agricultural and Food Chemistry.

ARS is the principal intramural scientific research agency in the U.S. Department of Agriculture.