Location: Water Management and Systems Research
Title: Detecting and Confirming Accelerated Atrazine Degradation in Illinois Soils Authors
|Shaner, Dale -|
|Hager, Aaron -|
Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 8, 2013
Publication Date: N/A
Interpretive Summary: Atrazine is widely used to control weeds in corn, sorghum and sugarcane. Farmers depend on atrazine to provide residual activity for several weeks. However, after multiple years of use the soil microbes can adapt and begin to degrade atrazine very quickly so that the residual control can decrease from 6 to 8 weeks down to 3 to 4 weeks. This phenomenon has been found throughout the U.S., but it has not been documented in the field in Illinois, a major corn producing state. This research shows that a simple lab assay can accurately detect enhanced atrazine degradation in fields that have a history of atrazine use. We also found that soil microbes can adapt to the application of atrazine within a growing season. These results mean that farmers should be aware that enhanced atrazine degradation occurs in Illinois and that they will not get the expected length of residual weed control in fields where atrazine has been used for multiple years.
Technical Abstract: Technical abstract: Enhanced degradation of atrazine has been documented in many parts of the world where the herbicide has been extensively used. Atrazine is widely used in corn in Illinois, but enhanced degradation in the field has not been documented. In this study, the dissipation of atrazine was measured in three fields. Two of the fields (URB-1 and URB-2) had not been treated with atrazine for three and four years, respectively whereas the third field (ORR-1) had received annual applications of atrazine for nine years. A laboratory assay conducted on soil collected from these fields prior to atrazine application indicated that soil from ORR-1 had enhanced atrazine degradation (half life (DT50) 2 d). Soil from Fields ORR-1 and URB-2 degraded atrazine much slower (DT50 was 13.4 and 6.1d, respectively). The rates of atrazine degradation in the field, were similar to those measured in the laboratory. The DT50s were 2.4, 8.4, and 12.6 d for ORR-1, URB-2 and URB-1, respectively. Testing the soils collected from the fields at the last sampling time showed that all of them had enhanced atrazine degradation, suggesting that the soil microbial populations had adapted to the presence of atrazine in the field.