Picolinic acids (aminopyralid and clopyralid) are commonly used herbicides in high latitude regions. Although permitted for use, unintended crop loss and other non-target impacts due to seasonal herbicide carryover are documented. Land managers seek information on soil residue persistence mechanisms with these compounds. Disparate persistence of aminopyralid vs clopyralid has been observed in Alaskan soils. To assess this, we characterized soils in the state of Alaska that span geographic variability throughout the region and assessed abiotic soil partitioning. FTIR and X-Ray Diffraction identified geographic variation in soil clay mineralogy. Sorption was found to correlate more strongly to soil pH and herbicide structure than soil temperature, origin, or type. Aminopyralid sorption reached pseudo-equilibrium after 24 hours. Desorption of the aminopyralid molecule occured after an additional 24 hour exposure to unspiked water. No significant change was seen for either sorption or desorption at 48 or 72 hour time points. Aminopyralid has shown significant sorption to all Alaskan soils tested, especially in acidic conditions, while clopyralid shows almost none. These findings help provide mechanistic insight into soil persistence in cold regions.<b> </b>

Picolinic acid persistence in Alaskan soils: One amine makes all the difference

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.