Field Persistence Studies with the Herbicide Glufosinate‐Ammonium in Saskatchewan Soils

Abstract

AbstractField plots on clay at Regina and Indian Head, and on clay loam at White City, Sask., were treated with glufosinate‐ammonium (the ammonium salt of DL‐homoalanin‐4‐ylmethylphosphinic acid) at a rate of about 1kg ha−1 during June or July 1988. At regular intervals, soil samples were taken from the 0‐ to 10‐cm and 10‐ to 20‐cm soil levels and extracted and analyzed gas chromatographically for glufosinate remaining. In addition, amounts of the soil metabolite MPPA [3‐(hydroxymethylphosphinyl)propionic acid] were also monitored. Providing there was adequate moisture, breakdown of the herbicide was rapid with no glufosinate detectable in any of the soils by the end of September 1988. In all soils the breakdown of MPPA was slower than that of glufosinate. Maximum amounts of the metabolite formed in the soils ranged from 0.26 kg ha−1 in the clay loam to 0.52 kg ha−1 in the clay at Regina. By the end of September there were 0.23, 0.06, and 0.17 kg ha−1 of MPPA in the 0‐ to 10‐cm soil level at Regina, White City, and Indian Head, respectively. There was no leaching of either glufosinate or MPPA to soil depths below 10 cm.