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Estimation of the Potential for Atrazine Transport in a Silt Loam Soil

ACS Symposium Series

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Abstract

The transport potential of the herbicide atrazine (2-chloro-4-ethyl-6-isopropyl-s-triazine) through a 1-meter-thick root zone of corn (Zea mays L.) in a silty-loam soil in Kansas was estimated for a 22-year period (1972-93) using the one-dimensional water-flow and solute-transport model LEACHM. Results demonstrate that, for this soil, atrazine transport is directly related to the amount and timing of rain that follows spring applications of atrazine. Two other critical transport factors were important in wet years - [1] variability in atrazine application rate, and [2] atrazine degradation rates below the root zone. Results demonstrate that the coincidence of heavy rain soon after atrazine application can cause herbicide to move below the rooting zone into depths at which biodegradation rates are assumed to be low but are often unknown. Atrazine that reaches below the rooting zone and persists in the underlying soil can subsequently be transported into ground water as soil water drains, typically after the growing season. A frequency analysis of atrazine concentrations in subsurface drainage, combined with field data, demonstrates the relative importance of critical transport factors and confirms a need for definitive estimates of atrazine-degradation rates below the root zone. The analysis indicates that periodic leaching of atrazine can be expected for this soil when rainfall that exceeds 20 cm/mo coincides with atrazine presence in soil.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Estimation of the Potential for Atrazine Transport in a Silt Loam Soil
Series title:
ACS Symposium Series
Volume
630
Year Published:
1996
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
ACS Symposium Series
First page:
101
Last page:
116
Number of Pages:
16