Mineralization of S-metolachlor in soil as affected by moisture content, application history, and association with glyphosate

Authors: DE AVILA, LUIS - Mississippi State University; ZEMOLIN, CARLA - Federal University Of Pelotas; Massey, Joseph; CAMAARGO, EDINALVO - Federal University Of Pelotas; FILES, MURICIO - Federal University Of Pelotas; CASSOL, GUILHERME - Federal University Of Pelotas

Submitted to: Advances in Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2023
Publication Date: 9/28/2023
Citation: De Avila, L.A., Zemolin, C.R., Massey, J., Camaargo, E.R., Files, M.C., Cassol, G.V. 2023. Mineralization of S-metolachlor in soil as affected by moisture content, application history, and association with glyphosate. Advances in Weed Science. 41. Article e020230033. https://doi.org/http://dx.doi.org/10.51694/AdvWeedSci/2023;41:00014.
DOI: https://doi.org/10.51694/AdvWeedSci/2023;41:00014

Interpretive Summary: This study investigated the influence of Roundup herbicide and the prior use of Dual herbicide on the complete breakdown (mineralization) of Dual herbicide (s-metolachlor) in topsoil. This information is important when assessing factors that impact the ability of soil-applied herbicides to control weeds in row cropping systems over time. The laboratory study found that a history (i.e., prior use) of Dual herbicide increased the rate at which Dual herbicide was degraded by microorganisms. The addition of Roundup herbicide to Dual herbicide also increased the rate of Dual herbicide breakdown in soil. These data are helpful in determinng how herbicide tank mixing and repeated applications of Dual affect its performance and environmental behavior in soil.

Technical Abstract: Herbicide dissipation in the soil is affected by several factors, including the herbicide application history of the soil, soil moisture, and whether the herbicide is co-applied with another herbicide. Laboratory studies were conducted to evaluate S-metolachlor mineralization in the soil as affected by soil moisture content, history of herbicide application, and association with glyphosate. 14C-S-metolachlor mineralization increased with increasing soil moisture content. The average cumulative mineralization of S-metolachlor at 63 days of incubation was 0.03, 0.8, and 1.8% in air-dried, field capacity, and saturated soil, respectively. The mineralization rate of S-metolachlor was greater under saturated conditions and affected by the association with glyphosate. Enhanced mineralization of S-metolachlor occurred in soil with a history of herbicide application. The average cumulative mineralization was 0.24% in soil without a history of herbicide application and 0.89% in soil with S-metolachlor application history.