Herbicide-Tolerant Crops Can Improve Water QualityApril 23, 2008The residual herbicides commonly used in the production of corn and soybean are frequently detected in rivers, streams, and reservoirs at concentrations that exceed drinking water standards in areas where these crops are extensively grown. When these bodies of water are used as sources of drinking water this contamination can lead to increased treatment costs or a need to seek alternative sources of supply. Additionally, these herbicides can have negative effects on aquatic ecosystems at concentrations well below their drinking water standards. When genetically modified, herbicide-tolerant, corn and soybean became commercially available in the 1990s it became possible to replace some of the problematic residual herbicides with strongly sorbed, short half-life, contact herbicides that may be more environmentally benign. By 2004 almost 90% of the soybean grown in the US was genetically modified for tolerance to the contact herbicide glyphosate (Roundup), which is currently the most widely used herbicide in the world. In a four-year study, researchers at the USDA-ARS's North Appalachian Experimental Watershed near Coshocton, OH compared relative losses of both herbicide types when applied at normal rates to seven small watersheds planted with Liberty-Linked corn or Roundup Ready soybean. In their report, published in the March-April issue of the Journal of Environmental Quality, soil scientists Martin Shipitalo and Lloyd Owens, and agricultural engineer Rob Malone, noted that losses of contact herbicides in surface runoff were usually much less than those for the residual herbicides, as a percentage of the amount of herbicide applied. Averaged for all soybean crop years, glyphosate loss was about one-seventh that of metribuzin and one half that of alachlor, residual herbicides it can replace. Similarly, average loss of the contact herbicide glufosinate (Liberty) was one-fourth that of atrazine, a residual corn herbicide it can replace. More importantly, according to project leader Martin Shipitalo, "The concentrations of the contact herbicides in the runoff never exceeded their established or proposed drinking water standards while the residual herbicides frequently exceeded their standards, particularly in the first few runoff events after application". Concentrations of atrazine in runoff were up to 240 times greater than its drinking water standard while alachlor concentrations were up to 700 times greater than its standard. Conversely, the maximum glyphosate concentration noted was nearly four times less than its standard. Glufosinate currently has no established standard, but was only detected at low concentrations and was below its detection limit 80 days after application. In light of increased economic incentives to grow more corn and soybean for biofuel production, these results suggest to farmers and the regulatory community that herbicide losses and concentrations in runoff can be reduced by planting herbicide-tolerant varieties of these crops and replacing some of the residual herbicides with the contact herbicides compared in this study. The full article is available for no charge for 30 days following the date of this summary. View the abstract at http://jeq.scijournals.org/cgi/content/abstract/37/2/401. The Journal of Environmental Quality, http://jeq.scijournals.org is a peer-reviewed, international journal of environmental quality in natural and agricultural ecosystems published six times a year by the American Society of Agronomy (ASA), Crop Science Society of America (CSSA), and the Soil Science Society of America (SSSA). The Journal of Environmental Quality covers various aspects of anthropogenic impacts on the environment, including terrestrial, atmospheric, and aquatic systems. The American Society of Agronomy (ASA) www.agronomy.org, is a scientific society helping its 8,000+ members advance the disciplines and practices of agronomy by supporting professional growth and science policy initiatives, and by providing quality, research-based publications and a variety of member services. American Society of Agronomy |
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| Related Herbicides Current Events and Herbicides News Articles Common herbicides and fibrates block nutrient-sensing receptor found in gut and pancreas According to new research from the Monell Center and the Mount Sinai School of Medicine, certain common herbicides and lipid-lowering fibrate drugs act in humans to block T1R3, a nutrient-sensing taste receptor also present in intestine and pancreas. Organic weed control for dandelions Spring and summer often find homeowners out in their yards, busily attempting to control the onslaught of dandelions in a quest for green, weed-free lawns. Scientists identify gene for resistance to parasitic 'witchweed' The parasitic flowering plant Striga, or "witchweed," attacks the roots of host plants, draining needed water and nutrients and leaving them unable to grow and produce any grains. Understanding how weeds are resistant to herbicides In a little over seven hours, University of Illinois weed scientist Patrick Tranel got more genetic information about waterhemp than in two years time in a lab. Limited data suggest possible association between Agent Orange exposure A new report from the Institute of Medicine finds suggestive but limited evidence that exposure to Agent Orange and other herbicides used during the Vietnam War is associated with an increased chance of developing ischemic heart disease and Parkinson's disease for Vietnam veterans. University of Minnesota research leads to new technology to protect human health Larry Wackett and Michael Sadowsky, members of the University of Minnesota's BioTechnology Institute, developed an enzyme that is used in Bioo Scientific's new MaxDiscovery™ Melamine Test kit, which simplifies the detection of melamine contamination in food. Herbicide diversity needed to keep Roundup effective Using a diverse herbicide application strategy may increase production costs, but a five-year Purdue University study shows the practice will drastically reduce weeds and seeds that are resistant to a popular herbicide. First evidence that weed killers improve nutritional value of a key food crop Scientists are reporting for the first time that the use of weed killers in farmers' fields boosts the nutritional value of an important food a crop. Extreme makeover chemistry style In revisiting a chemical reaction that's been in the literature for several decades and adding a new wrinkle of their own, researchers with Berkeley Lab and the University of California (UC) Berkeley have discovered a mild and relatively inexpensive procedure for removing oxygen from biomass. Individuals who apply pesticides are found to have double the risk of blood disorder A study involving 678 individuals who apply pesticides, culled from a U.S. Agricultural Health Study of over 50,000 farmers, recently found that exposure to certain pesticides doubles one's risk of developing an abnormal blood condition called MGUS (monoclonal gammopathy of undetermined significance) compared with individuals in the general population. More Herbicides Current Events and Herbicides News Articles |
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