Sorption of Simazine andS-Metolachlor to Soils from a Chronosequence of Turfgrass Systems

Abstract

Pesticide sorption by soil is among the most sensitive input parameters in many pesticide-leaching models. For many pesticides, organic matter is the most important soil constituent influencing pesticide sorption. Increased fertility, irrigation, and mowing associated with highly maintained turfgrass areas result in constant deposition of organic material, creating a soil system that can change drastically with time. Changes in soil characteristics could affect the environmental fate of pesticides applied to turfgrass systems of varying ages. Sorption characteristics of simazine andS-metolachlor were determined on five soils from bermudagrass systems of increasing ages (1, 4, 10, 21, and 99 yr) and compared to adjacent native pine and bare-ground areas. Surface soil (0 to 5 cm) and subsurface soil (5 to 15 cm) from all sites were air-dried and passed through a 4-mm sieve for separation from plant material. Using a batch-equilibrium method, sorption isotherms were determined for each soil. Data were fit to the Freundlich equation, andKd(soil sorption coefficient) andKoc(organic carbon sorption coefficient) values were determined. Sorption and soil system age were directly related to organic matter content in the soil. Sorption of both herbicides increased with age of the soil system and was greatest on the surface soil from the oldest bermudagrass soil system. Herbicide sorption decreased at greater soil depths with lower organic matter. Greater amount of14C–simazine sorbed to subsurface soil of the oldest turfgrass system compared to14C–S-metolachlor. Results indicate that as bermudagrass systems age and accumulate higher organic matter levels increased herbicide sorption may decrease the leaching potential and bioavailability of simazine andS-metolachlor.

Effect of soil type and organic manure on adsorption–desorption of flubendiamide

“…This also indicates that adsorption process was reversible. The flubendiamide K d values were generally smaller than the K F of adsorption process in both two soil types because of nonlinearity in sorption, as reported in triazine herbicides by Gannon et al 2013. Adsorption-desorption studies with 1 % organic manure-treated soil revealed that Freundlich coefficient K F for adsorption process also increased in the two tested soils; 8.80 ml/g (organic manure-treated red soil) and 3.90 ml/g (organic manure-treated black soil) as compared to without amended soil.…”

Selectivity of Herbicide Associations with Chemical Protector in the Treatment of Sweet Sorghum Hybrid Seeds

“…However, high soil contents of clay and organic matter may also have positively influenced culture selectivity due to the lower herbicide availability for soil solution, since the sorption of atrazine (Procópio et al, 2001), (3) 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 5 isoxaflutole (Oliveira Jr et al, 2006) and S-metolachlor (Gannon et al, 2013) herbicides presents direct correlation with soil organic matter.…”

S-metolachlor and rainfall effects on sweetpotato (Ipomoea batatas L. [Lam]) growth and development

“…Total marketable SR weight decline was more severe with the rainfall treatment, which could be attributed to low organic matter (0.68%) and clay (5.8%) content of the soil used in this study. S-metolachlor mobility in the soil solution has been reported to be affected by high organic matter content (>2.0%), clay mineral content and surface area (Nennemann et al, 2001;Senseman, 2007;Alletto et al, 2013;Gannon et al, 2013). In a peanut study, Cardina and Swann (1988) observed delayed emergence and reduced growth when irrigation followed metolachlor application at planting.…”