Pesticide impact: Comparing lab, field-scale results

(Press-News.org) MADISON, WI, JUNE 15, 2011 -- Assessing the environmental risk of pesticide use is an important, complex task that requires knowledge of the equilibrium sorption parameter. This helps researchers assess the risk of pesticides leaching into groundwater. For cost-effective assessments, this is usually determined through batch experiments that find the amount of pesticide in test soils as a function of concentration at a constant temperature. These experimental conditions differ considerably from real-world conditions. Thus, the validity of the data collected using this method is widely debated.

Recently, scientists from Germany and New Zealand evaluated parameters from different experiments that used the same pesticides and soils. Using this data, scientists analyzed the relationships between flow velocities of soil water, the residence time of the pesticides in the soil and the sorption parameters. Results from the study were published in the May-June 2011 issue of the Journal of Environmental Quality.

Scientists found that the range of sorption constants increased with increasing water velocity. Only for water velocity values lower than 35 mm/day, the range of sorption constants was between zero and one. Typically, these values have been obtained in field-scale experiments run under unsaturated flow conditions using undisturbed soil columns. The scientists showed that replacing equilibrium constants obtained from standard measurement protocols for pesticide registration purposes would lead to misinterpretation of the data. Experiment operation times greater than one day, with a typical duration of several days to weeks, yield the most realistic results.

According to the authors, it is also important to consider sorption and desorption kinetics. The movement of pesticides into a soil matrix was found to depend strongly on the amount of accessible sorption sites, which is determined by soil water content and soil structure. An understanding of this movement will require experimental protocols that take soil structure and soil moisture content into account when researching the impact of pesticides.

### The full article is available for no charge for 30 days following the date of this summary. View the abstract at https://www.agronomy.org/publications/jeq/abstracts/40/3/879.

The Journal of Environmental Quality 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.

The Crop Science Society of America (CSSA), founded in 1955, is an international scientific society comprised of 6,000+ members with its headquarters in Madison, WI. Members advance the discipline of crop science by acquiring and disseminating information about crop breeding and genetics; crop physiology; crop ecology, management, and quality; seed physiology, production, and technology; turfgrass science; forage and grazinglands; genomics, molecular genetics, and biotechnology; and biomedical and enhanced plants.

CSSA fosters the transfer of knowledge through an array of programs and services, including publications, meetings, career services, and science policy initiatives. For more information, visit www.crops.org.

The Soil Science Society of America (SSSA) is a progressive, international scientific society that fosters the transfer of knowledge and practices to sustain global soils. Based in Madison, WI, SSSA is the professional home for 6,000+ members dedicated to advancing the field of soil science. It provides information about soils in relation to crop production, environmental quality, ecosystem sustainability, bioremediation, waste management, recycling, and wise land use.

SSSA supports its members by providing quality research-based publications, educational programs, certifications, and science policy initiatives via a Washington, DC, office. Founded in 1936, SSSA celebrates its 75th Anniversary this year (2011). For more information, visit www.soils.org or follow @SSSA_soils on Twitter.