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Soil Moisture and Metolachlor Volatilization Observations over Three Years
Author(s) -
Gish Timothy J.,
Prueger John H.,
Kustas William P.,
Daughtry C.S.T.,
McKee Lynn G.,
Russ Andy,
Hatfield Jerry L.
Publication year - 2009
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2008.0276
Subject(s) - metolachlor , soil water , water content , volatilisation , environmental science , surface water , soil science , field capacity , hydrology (agriculture) , moisture , chemistry , agronomy , pesticide , environmental engineering , geology , atrazine , geotechnical engineering , organic chemistry , biology
A 3‐yr study was conducted to focus on the impact of surface soil water content on metolachlor (2‐chloro‐ N ‐(2‐ethyl‐6‐methylphenyl)‐ N ‐(2‐methoxy‐1‐methylethyl) acetamide) volatilization from a field with different surface soil water regimes created by subsurface water flow paths. Metolachlor vapor fluxes were measured at two locations within the field where local meteorological and soil conditions were relatively constant, except for surface soil water content, which differed significantly. Surface soil water content at the two sites differed in response to the presence of subsurface flow pathways. Detailed soil moisture observations over the duration of the study showed that for the first 2 yr (2004 and 2005), surface soil water contents at the dry location (V1) were nearly half those at the wetter location (V2). Cumulative metolachlor vapor fluxes during 2004 and 2005 at V1 were also about half that at V2. In the third year (2006), early‐season drought conditions rendered the soil water content at the two locations to be nearly identical, resulting in similar metolachlor volatilization losses. Analysis of infrared soil surface temperatures suggests a correlation between surface soil temperatures and metolachlor volatilization when soils are wet (2004 and 2005) but not when the soils are dry (2006). Field‐averaged metolachlor volatilization losses were highly correlated with increasing surface soil water contents ( r 2 = 0.995).