AUTC project number: 107024
David L. Barnes (UAF)
This project worked with AKDOT&PF, the USDA Agricultural Research Service (Subarctic Agricultural Research Unit), and the Salcha-Delta Soil & Water Conservation District to develop an integrated plan for roadside vegetation control. The most salient study results concern the half-lives determined for each herbicide sample collected from the Delta Junction test site. Samples obtained up to 27 days (prior to an increase in herbicide concentration found in the soil following a relatively large rain event) after application indicate that the attenuation rates are similar to rates reported in the literature for more temperate soils. Further, both 2,4-D and triclopyr are found in the soil at some concentration one year after application, indicating that herbicide persistence is longer compared to reported results from more temperate regions.Researchers also found that the percentage of herbicide mass measured at each sampling event compared to the mass applied was small and relatively consistent for each site through the course of the study. Our conclusion is that plant uptake and metabolism play a key role in the attenuation of herbicides applied to subarctic soils.