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North America is a continent in the Earth's northern hemisphere and almost fully in the western hemisphere, bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the south and west by the North Pacific Ocean; South America lies to the southeast. It covers an area of about 24,480,000 km² (9,450,000 sq mi), or about 4.8% of the planet's surface. As of July 2002, its population was estimated at more than 514,000,000. It is the third largest continent in area, after Asia and Africa, and is fourth in population after Asia, Africa, and Europe.

Etymology

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A number of theories exist regarding the naming of North and South America. The most widely recognized is that they are named after Amerigo Vespucci, who was the first European to suggest that the Americas were not the East Indies, but a New World, previously undiscovered by Europeans. The second and less generally accepted is that the continents are named after an English merchant named Richard Amerike from Bristol, who is believed to have financed John Cabot's voyage of discovery from England to Newfoundland in 1497. A third and minutely explored belief that has been advanced is that America was named for a Spanish sailor bearing the ancient Visigothic name of 'Amairick'.

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USDA Agricultural Research Service

Exploring Earthworms
Fri, 18 Jul 2008 08:40:00 -0500
The right earthworms can make home septic systems work better. Photo courtesy of Flagstaffotos. Wormholes—yet another avenue for pollution?   ARS honors scientist for soil nitrogen research   A high-tech look at soil composition Role of Earthworms in Soil Explored By Don Comis July 18, 2008 The right earthworms can make home septic systems work better. The wrong ones could do the opposite. That’s the finding in a study of worm populations living in the soil near trenches receiving septic tank flow outside five single family homes in Arkansas. Carrie L. Hawkins of the University of Arkansas at Fayetteville performed the study in collaboration with Agricultural Research Service (ARS) soil scientist Martin J. Shipitalo of the North Appalachian Experimental Watershed in Coshocton, Ohio. The scientists found that the worms were favoring the area near the trenches because they were feeding on the household wastes discharged in the trenches. They found fives species of earthworms. None of the species were deep-burrowers like nightcrawlers. Their burrowing near the surface actually helped the septic wastewater spread through the soil more evenly, resulting in better cleansing of the water. Had they been nightcrawlers, the worm burrows might have drained the trenches so fast that it would bypass the soil filtering. The results of this study will be published in the journal Applied Soil Ecology and are currently online. The earthworm study is part of a longstanding series of worm studies across the country by Shipitalo, ARS colleagues at Coshocton and elsewhere, and cooperating university scientists. This body of earthworm knowledge is one of many aspects of ARS research on soils that is incorporated into the Smithsonian Institution's Soil Exhibition, which opens on July 19 and ends December 31, 2010. The exhibition is at the Smithsonian's National Museum of Natural History in Washington, D.C., and is called "Dig it! The Secrets of Soils." Ted Zobeck and Michael Russelle, at ARS labs in Texas and Minnesota, respectively, are state liaisons for the exhibit. ARS scientists at the National Soil Tilth Laboratory in Ames, Iowa, contributed heavily to the exhibition, as did the late Dennis Linden in Minnesota. The U.S. Department of Agriculture (USDA) is a lead sponsor of the exhibition through the Soil Science Society of America. ARS is a scientific research agency of the USDA.
Switchgrass May Mean Better Soil
Thu, 17 Jul 2008 09:07:00 -0500
Read the magazine story to find out more. Native grasses like switchgrass may contribute to soils with higher levels of glomalin, a glycoprotein that helps store carbon and may increase the value of the grass as a source of ethanol. Click the image for more information about it. Glomalin: A key to switchgrass ethanol success   Global warming may lower grassland quality   Bringing back the native grasses of California Switchgrass May Mean Better Soil By Don Comis July 17, 2008 Soils with native grasses such as switchgrass have higher levels of a key soil component called glomalin than soils planted to non-native grasses, according to a study by the Agricultural Research Service at two locations in Mandan, N.D. Kristine Nichols, a microbiologist with the ARS Northern Great Plains Research Laboratory in Mandan, conducted the study. Glomalin is a sugar-protein compound that might trigger the formation of soil. The more glomalin in a given soil, the better and less erosion-prone that soil probably is. In 2004, Nichols collected soil from under grass plots established between 1987 and 2002. The amount of glomalin in the soil increased as the degree of interdependence between plants and the arbuscular mycorrhizal fungi increased. These fungi produce glomalin and live inside plant roots and the surrounding soil. That interdependence is greatest in warm-season native grasses such as switchgrass, blue grama, big bluestem and indiangrass. Further evidence that soils underneath native grasses are higher in glomalin came from another study on rangeland areas at Mandan and near Platte, S.D. In an earlier study, Nichols analyzed samples from undisturbed soils with native vegetation in Maryland, Georgia and Colorado. According to her analysis, glomalin stored a large percentage of the carbon found in those soils and contributed greatly to soil fertility. On average, glomalin stored 15 percent of the soil carbon, with the highest amount—30 percent— in a Colorado soil and the lowest amount—9 percent—in a Georgia soil. These results are similar to those from other soil samples taken around the world. The increased glomalin and underground carbon storage observed with switchgrass adds to its value as a potential source of cellulosic ethanol. Nichols uses glomalin measurements as a quick guide to evaluate how "soil-friendly" farming or rangeland practices actually are. She originally worked with soil scientist Sara Wright, who discovered and named glomalin in 1996. Wright has since retired. Read more about the research in the July 2008 issue of Agricultural Research magazine. ARS is a scientific research agency of the U.S. Department of Agriculture.
Spice Extracts Battle Bacteria
Mon, 14 Jul 2008 08:46:00 -0500
Read the magazine story to find out more. Extracts from plants such oregano were active against several foodborne pathogens, including E. coli O157:H7, Listeria monocytogenes, and Salmonella enterica, in ARS tests. Photo courtesy of McCormick & Company, Inc. Pathogen genes targeted in studies to protect salad veggies   Protecting romaine lettuce from pathogens   "Bad-Guy" bacterium's genetic structure probed Spice-Rack Favorites Battle E. coli and Other Foodborne Pathogens By Marcia Wood July 14, 2008 Herbs and spices like oregano, thyme, cinnamon and clove do more than add pleasing flavors and aromas to familiar foods. The oils from these plants, or compounds extracted from those oils, pack a powerful, antimicrobial punch—strong enough to help quell such foodborne pathogens as Escherichia coli O157:H7. That's according to Agricultural Research Service (ARS) chemist Mendel Friedman, who several years ago evaluated the bacteria-bashing power of these and dozens of other plant compounds. Now, some of the compounds that Friedman and co-investigators determined were the strongest combatants of E. coli, Salmonella enterica, Campylobacter jejuni, or Listeria monocytogenes in the 2002 study are being tapped for new research focused on food safety. For example, Friedman, research leader Tara H. McHugh, and other scientists at the ARS Western Regional Research Center in Albany, Calif., are evaluating the highest-ranking botanical bactericides as potential ingredients in what are known as edible films. A thin, pliable, edible film for the future might be made of puréed spinach spiked with carvacrol, the compound responsible for oregano's ranking as a top fighter of E. coli in the Friedman study. The scientists want to find out whether adding small squares of carvacrol-enhanced spinach purée film to bags of chilled, ready-to-eat spinach leaves would help protect this salad green against E. coli. Friedman is also exploring other new uses of the top-rated botanicals from the earlier study. That investigation, which he conducted with technician Philip R. Henika and research leader Robert E. Mandrell at Albany, was the most extensive of its kind at the time it was published. Also notable was the common basis of comparison, which the team established by inventing new methods to prepare and test all of the samples. For even more consistency, the scientists used the same bacterial strains—from the same suppliers—throughout the investigation. Read more about the research in the July 2008 issue of Agricultural Research magazine. ARS is a scientific research agency of the U.S. Department of Agriculture.

USDA - National Agricultural Statistics Service Reports

Milk Production
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