Agronomic and environmental implications of enhanced s-triazine degradation

Authors

  • L Jason Krutz,

    Corresponding author
    1. United States Department of Agriculture, Agriculture Research Service, Crop Production Systems Research Unit, Stoneville, MS, USA
    • United States Department of Agriculture, Agriculture Research Service, Crop Production Systems Research Unit, PO Box 350, Stoneville, MS 38776, USA.
    Search for more papers by this author
  • Dale L Shaner,

    1. United States Department of Agriculture, Agricultural Research Service, Water Management Research Unit, Fort Collins, CO, USA
    Search for more papers by this author
  • Mark A Weaver,

    1. United States Department of Agriculture, Agricultural Research Service, Biological Control of Pests Research Unit, Stoneville, MS, USA
    Search for more papers by this author
  • Richard MT Webb,

    1. United States Department of the Interior, United States Geological Survey, Lake Wood, Colorado, USA
    Search for more papers by this author
  • Robert M Zablotowicz,

    1. United States Department of Agriculture, Agriculture Research Service, Crop Production Systems Research Unit, Stoneville, MS, USA
    Search for more papers by this author
  • Krishna N Reddy,

    1. United States Department of Agriculture, Agriculture Research Service, Crop Production Systems Research Unit, Stoneville, MS, USA
    Search for more papers by this author
  • Yanbo Huang,

    1. United States Department of Agriculture, Agriculture Research Service, Crop Production Systems Research Unit, Stoneville, MS, USA
    Search for more papers by this author
  • Steven J Thomson

    1. United States Department of Agriculture, Agriculture Research Service, Crop Production Systems Research Unit, Stoneville, MS, USA
    Search for more papers by this author

Abstract

Novel catabolic pathways enabling rapid detoxification of s-triazine herbicides have been elucidated and detected at a growing number of locations. The genes responsible for s-triazine mineralization, i.e. atzABCDEF and trzNDF, occur in at least four bacterial phyla and are implicated in the development of enhanced degradation in agricultural soils from all continents except Antarctica. Enhanced degradation occurs in at least nine crops and six crop rotation systems that rely on s-triazine herbicides for weed control, and, with the exception of acidic soil conditions and s-triazine application frequency, adaptation of the microbial population is independent of soil physiochemical properties and cultural management practices. From an agronomic perspective, residual weed control could be reduced tenfold in s-triazine-adapted relative to non-adapted soils. From an environmental standpoint, the off-site loss of total s-triazine residues could be overestimated 13-fold in adapted soils if altered persistence estimates and metabolic pathways are not reflected in fate and transport models. Empirical models requiring soil pH and s-triazine use history as input parameters predict atrazine persistence more accurately than historical estimates, thereby allowing practitioners to adjust weed control strategies and model input values when warranted. Published in 2010 by John Wiley & Sons, Ltd.

Ancillary