Sub-Arctic Field Degradation of Metsulfuron-Methyl in Two Alaskan Soils and Microbial Community Composition Effects

Abstract

Metsulfuron-methyl is a sulfonylurea herbicide, primarily with postemergence activity but also with occasional pre-emergent activity, used for control of weeds and woody plants on agricultural lands and natural areas. The active ingredient is popular in Alaska as Ally XP formulation; little is known about its high-latitude environmental behavior and potential adverse impacts on soil health in cold regions. Our study determined field degradation rates at two experimental farms in Alaska and assessed whether laboratory-incubated soil amended at 1× or 100× label rates would adversely impact microbial community diversity. DT50 was observed at 4.12–5.13 days, with the compound below 1 μg/kg detection limit at 90 days. Interestingly, this is faster than the reported range of field half-lives in the literature (7–42 days). Microbial community composition was not affected by MSM at both 1× and 100× rates. High-latitude regions exhibit extreme summer photoperiods that may exacerbate the MSM degradation/dissipation rate; we postulate that timing of application may have large impacts on MSM attenuation.