The 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.
Sara Uttech | EurekAlert!
Climate change, population growth may lead to open ocean aquaculture
05.10.2017 | Oregon State University
New machine evaluates soybean at harvest for quality
04.10.2017 | University of Illinois College of Agricultural, Consumer and Environmental Sciences
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
17.10.2017 | Life Sciences
17.10.2017 | Life Sciences
17.10.2017 | Earth Sciences