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Effects of repeated glyphosate applications on soil microbial community composition and the mineralization of glyphosate
Author(s) -
Lancaster Sarah H,
Hollister Emily B,
Senseman Scott A,
Gentry Terry J
Publication year - 2010
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.1831
Subject(s) - glyphosate , mineralization (soil science) , microbial population biology , soil microbiology , agronomy , pesticide , biology , chemistry , bacteria , food science , ecology , soil water , genetics
Background: Repeated applications may have a greater impact on the soil microbial community than a single application of glyphosate. Experiments were conducted to study the effect of one, two, three, four or five applications of glyphosate on soil microbial community composition and glyphosate mineralization and distribution of 14 C residues in soil. RESULTS: Fatty acid methyl esters (FAMEs) common to gram‐negative bacteria were present in higher concentrations following five applications relative to one, two, three or four applications both 7 and 14 days after application (DAA). Additionally, sequencing of 16S rRNA bacterial genes indicated that the abundance of the gram‐negative Burkholderia spp. was increased following the application of glyphosate. The cumulative percentage 14 C mineralized 14 DAA was reduced when glyphosate was applied 4 or 5 times relative to the amount of 14 C mineralized following one, two or three applications. Incorporation of 14 C residues into soil microbial biomass was greater following five glyphosate applications than following the first application 3 and 7 DAA. CONCLUSION: These studies suggest that the changes in the dissipation or distribution of glyphosate following repeated applications of glyphosate may be related to shifts in the soil microbial community composition. Copyright © 2009 Society of Chemical Industry