The objective of this research was to investigate the use of reference compounds (minimum and maximum Kd values) during the determination of pesticide adsorption with different soil to solution ratios. Ten soils, five herbicides (2,4-D, atrazine, clomazone, S-metolachlor, and saflufenacil) and three soil:solution ratios (1:3, 1:5, and 1:10) were selected to conduct the study. Ultrapure water without CaCl2 was used to perform the batch equilibrium. Furthermore, aqueous solution containing CaCl2 (0.01 M) was used for an additional study using the 1:5 ratio. Results indicated that CaCl2 decreased pH of soils affecting adsorption results of weak acid herbicides such as 2,4-D. Soil to solution ratios affected Kd values, but responses were dependent of the soil-pesticide interaction. The use of reference compounds during Kd estimation allowed for calculation of a conceptual adsorption window (AW) generating a more comprehensive set of data with alternatives for comparison of soils and methods.

Development of an adsorption window for pesticides: A potential alternative to comparing soil adsorption values

244th National Meeting (2012)

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