Sorption and mobility of flumetsulam in several soils

Abstract

Flumetsulam sorption and mobility studies were conducted on surface (0 to 15 cm) and subsurface (30 to 46 cm) soil of several southern soils. In a batch equilibrium study using a 1:1 ratio of soil–0.01 M CaCl2, flumetsulam adsorbed ranged from 2.9 to 48.7% and from 4.2 to 63.3% on surface and subsurface soils, respectively. Herbicide soil–solution distribution (Kd) and organic carbon (Koc) coefficients ranged from 0.03 to 0.95 and from 5.1 to 77.1, respectively, in surface soils and from 0.04 to 1.72 and from 7.5 to 325.5, respectively, in subsurface soils. Kd and Koc were correlated with humic and organic matter in surface soils. Kd was correlated with extractable Fe, whereas Koc was inversely correlated to pH in subsurface soils. A desorption study using 0.01 M CaCl2 as an extractant on the Captina silt loam surface soil demonstrated that three to four washes were required to desorb more than 94% of the flumetsulam adsorbed over several equilibration times. Mobility studies on soil thin-layer chromatography plates demonstrated that flumetsulam and imazaquin had similar values, ranging from 0.50 to 0.90 and 0.59 to 0.90, respectively, in the surface soils, and both compounds had the same range of mobility in subsurface soils, with Rf values between 0.60 and 0.93. At both soil depths, Kd and Koc were inversely correlated with the Rf of flumetsulam.