Volatilization of Fonofos, Chlorpyrifos, and Atrazine from Conventional and No‐Till Surface Soils in the Field

Abstract

AbstractWe measured the effect of no‐till on pesticide volatilization in a side‐by‐side comparison of volatilization rates from no‐till (NT) and conventionally tilled (CT) fields. Volatilization rates were determined using the theoretical profile shape method for 10 of the 26 d following application. Soil and mulch residues were also measured. Volatilization losses of fonofos (O‐ethyl S‐phenyl ethylphosphonodithioate) and chlorpyrifos [O,O‐diethyl O‐(3,5,6‐trichloro‐2‐pyridyl) phosphorothioate] from the NT field were two to four times volatilization losses from the CT field. As much as one‐half of the application volatilized during 26 d. Volatilization of atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐ 1,3,5‐triazine‐2,4‐diamine] was also greater from NT, but only 1 to 2% of the application volatilized. Maximum volatilization rates were usually measured at midday, indicating that volatilization was not limited by soil dryness. Over the 26 d of the experiment, volatilization decreased faster than pesticide residue was depleted, suggesting residues were becoming more strongly sorbed to soil and/or mulch, or were becoming less accessible to the surface.