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This article in JEQ

  1. Vol. 29 No. 3, p. 936-947
     
    Received: May 7, 1999


    * Corresponding author(s): gaynorj@em.agr.ca
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doi:10.2134/jeq2000.00472425002900030032x

Tillage and Controlled Drainage-Subirrigated Management Effects on Soil Persistence of Atrazine, Metolachlor, and Metribuzin in Corn

  1. J. D. Gaynor *,
  2. C. S. Tan,
  3. H. Y. F. Ng,
  4. C. F. Drury,
  5. T. W. Welacky and
  6. I. J. vanWesenbeeck
  1. Greenhouse and Processing Crops Research Centre, Agriculture and Agri-Food Canada, Harrow, ON Canada N0R 1G0.
    NWR Environment Canada, Burlington, ON Canada L7R 4A6.
    DowElanco, Environmental Fate, Bldg 306-Az, 9330 Zionsville Rd., Indianapolis, IN 46268.

Abstract

Abstract

The occurrence of herbicides in surface waters necessitates the development of management practices to reduce herbicide loss through tile drainage and surface runoff. Four tillage-intercrop systems: moldboard plow (MB), moldboard plow with rye grass (Lolium multiflorum Lam.) intercrop (MB+IC), soil saver (SS), and soil saver with rye grass intercrop (SS+IC), and two water table management treatments: controlled drainage-subirrigation (CDS) and no control drainage (D) were investigated for their effect on herbicide persistence. Atrazine [2-chloro-4-ethylamino-6-isopropylamino-s-triazine] (1.1 kg ha−1), metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] (0.5 kg ha−1), and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] (1.68 kg ha−1) were strip applied in a corn (Zea mays L.) management system to reduce herbicide inputs 50%. Tillage-intercrop system had little consistent effect on soil residues of the herbicides at 0- to 10-cm depth. Control drainage-subirrigation decreased haif-life of atrazine and metolachlor in one of two years. Half-life for atrazine ranged from 34 to 56 d, metribuzin 24 to 35 d, and metolachlor 40 to 79 d, with longer half-life in dry years. Des-ethyl atrazine [2-chloro-4-amino-6-isopropylamino-s-triazine], the major metabolite of atrazine, persisted along with atrazine and metolachlor to the next planting season. Less than 10% of the original herbicide application was recovered the year following application. It was concluded that environmental factors such as rain affect herbicide residues more than cultural practices.

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