Picloram Movement in Soil Solution and Streamflow from a Coastal Plain Forest

Abstract

Picloram (4-amino-3,5,6-trichloropicolinic acid) was aerially applied to P longleaf pine (Pinus palustris L.) site in the upper constnl plain of Alabama to control kudzu [Purraria lobota (Willd.) Ohwi]. Pellets (10% a.i.) were spread at the rate of 56 kg ha^-1 on loamy sand Typic Knnhspludult soils. Movement of this herbicide was monitored with mineral soil samples, tension-cup lysimeters, flow- proportional streamilow samplers, and discrete samplers. Piclornm levels in the upper 15 cm of mineral soil peaked at 0.96 to 2.25 mg kg^-1 25 d after application, depending on slope position, and declined to 0.13 to 0.29 mg kg^-1 1 yr later. In soil solution, picloram was detected at P depth of 0.4 m between 26 and 273 d after application.Only 4 of IS lysimeters consistently contained detectable residues. Maximum picloram levels in soil solution were 130, 450, and 191 mg m^-3 for ridge, midslope, and toe-slope positions, respectively. Downstream monitoring began 4 d after the herbicide application, and art initial concentration of 68 mg m^-3 of picloram was detected. The maximum downstream concentration of 77 mg m^-3 occurred 18 d after the application, immediately after the second storm event. Downstream levels dropped to

Citation

Michael, Jerry L.; Neary, D.G.; Wells, M.J.M. 1989. Picloram Movement in Soil Solution and Streamflow from a Coastal Plain Forest. Jounral of Environmental Quality. 18(1): 89-95. 1989