Submitted to: Journal of Society of Environmental Toxicology and Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 7, 1998
Publication Date: N/A
Interpretive Summary: An optimum balance of herbicide bound by soils and taken up by weeds must be struck for effective weed control. The balance is affected by several soil properties and management factors. Some soil properties (like soil organic matter and landscape position) and management factor (like tillage) were investigated to determine their influence on the amount tof herbicide bound by soil. Soils from both Iowa and South Carolina were used. We found that soil properties that enhanced soil organic matter accumulation also increased herbicide binding. For instance, soils in depressional areas of Iowa and under conservation tillage in South Carolina had high amounts of soil organic matter. These soils were capable of binding more herbicide than soils in sloping position and under conventional tillage. To insure effective weed control and prevent herbicide leaching to ground water, we will need to adjust herbicide application rates to account for the effects of soil properties and management factors on herbicide sorption.
Technical Abstract: The sorption of herbicide by soil particles has an important influence on their behavior and movement in soil. The sorption process is controlled by a few relevant soil properties and management factors. Characterizing their effects on herbicide sorption is necessary to promote management practices, which can potentially reduce herbicide ground and surface water contamination. We have evaluated the effects of two soil properties: soil organic carbon (SOC) content, landscape position, and a management factor like tillage in Iowa and South Carolina soils on the sorption of atrazine. We also have evaluated their effects with potential atrazine fate in the soil environment. In both Iowa and South Carolina, the magnitude of atrazine sorption was strongly correlated with the SOC content, landscape position, and tillage management. Landscape position was particularly important in Iowa soils because depressional areas (potholes) on the Wisconsinan glacial surface are SOC-enriched and can sorb more atrazine than soils in sloping positions. Because of the higher amount of sorption, soils in the potholes are capable of reducing the amount of atrazine leached through the soil profile. Herbicide management strategies will require some adjustments in order to account for the effects of SOC, landscape position, and tillage management on atrazine sorption in order to augment effective weed control and prevent herbicide movement to ground water.