Abstract
Herbicide mineralization 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. The objective of this work was 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, 0.80, and 1.80% 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. Greater mineralization of S-metolachlor occurred in cornfield soil with a history of S-metolachlor application. The average cumulative mineralization was 0.24% in cornfield and 0.89% in non-cultivated area. We can conclude that the higher the soil moisture content the higher S-metolachlor mineralization and that the mixture of this herbicide with glyphosate increased its degradation compared to the application of the herbicide alone. While there is evidence suggesting enhanced degradation of S-metolachlor in soil previously subjected to corn cultivation and S-metolachlor application, drawing a definitive conclusion is challenging due to the influence of sorption observed in our dataset.
Degradation; Herbicide; Environmental Fate; Enhanced Mineralization