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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #332550

Research Project: Management Strategies to Sustain Irrigated Agriculture with Limited Water Supplies

Location: Water Management and Systems Research

Title: Dissipation and leaching of pyroxasulfone and s-metolachlor

Author
item Westra, Eric - Colorado State University
item Shaner, Dale - Retired ARS Employee
item Westra, Philip - Colorado State University
item Chapman, Philip - Colorado State University

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2013
Publication Date: 1/1/2014
Citation: Westra, E.P., Shaner, D.L., Westra, P.H., Chapman, P.L. 2014. Dissipation and leaching of pyroxasulfone and s-metolachlor. Weed Technology. 28(1):72-81. doi:10.1614/WT-D-13-00047.1.

Interpretive Summary: Herbicide dissipation and mobility influences persistence in the soil and potential for damage to non-resistant crops. Both traits may be influenced by soil type and conditions. In this study, the dissipation of two herbicides, Pyroxasulfone and S-metolachlor, in two soils, Nunn fine clay loam and Olney fine sandy loam, were measured over two years. S-metolachlor dissipated more quickly than Pyroxasulfone. Both herbicides dissipated more quickly in the coarser soil when rainfall was higher than normal, likely due to leaching below the 30 cm layer. Pyroxasulfone tended to be more mobile under all conditions.

Technical Abstract: Pyroxasulfone dissipation and mobility in the soil was evaluated and compared to S-metolachlor in 2009 and 2010 at two field sites in northern Colorado, on a Nunn fine clay loam, and Olney fine sandy loam soil. Pyroxasulfone dissipation half-life (DT50) values varied from 47 to 134 d, and those of S-metolachlor ranged from 39 to 63 d. Between years, herbicide DT50 values were similar under the Nunn fine clay loam soil. Under the Olney fine sandy loam soil, dissipation in 2009 was minimal under dry soil conditions. In 2010, under the Olney fine sandy loam soil, S-metolachlor and pyroxasulfone had half-lives of 39 and 47 d, respectively, but dissipation rates appeared to be influenced by movement of herbicides below 30 cm. Herbicide mobility was dependent on site-year conditions, in all site-years pyroxasulfone moved further downward in the soil profile compared to S-metolachlor.