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This article in JEQ

  1. Vol. 32 No. 6, p. 2216-2222
     
    Received: Dec 12, 2002
    Published: Nov, 2003


    * Corresponding author(s): shang@agro.uncor.edu
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doi:10.2134/jeq2003.2216

Behavior of 14C-Atrazine in Argentinean Topsoils under Different Cropping Managements

  1. S. Hang *a,
  2. E. Barriusob and
  3. S. Houotb
  1. a University of Córdoba, CC 509, 5000 Córdoba, Argentina
    b National Institute of Agronomical Research, Environment and Arable Crops, BP 01, 78850 Thiverval-Grignon, France

Abstract

Atrazine (6-chloro-N 2–ethyl-N 4–isopropyl-1,3,5-triazine-2,4-diamine) behavior was studied in four surface soils during incubations in laboratory conditions. Soils were chosen in relation to their cropping management (tillage and no tillage) and crop rotation system (continuous soybean [Glycine max (L.) Merr.] and maize (Zea mays L.)–soybean rotation). A natural soil under brushwood was sampled as a reference. Atrazine use in field conditions was associated with maize cropping, thus only one soil received atrazine every other year. Atrazine behavior was characterized through the balance of 14C-U-ring atrazine radioactivity among the mineralized fraction, the extractable fraction, and the nonextractable bound residues. Soil organic matter capacity to form bound residues was characterized using soil size fractionation. Accelerated atrazine mineralization was only observed in the soil receiving atrazine in field conditions. Atrazine application every other year was enough to develop a microflora adapted to triazine ring mineralization. Bound residue formation was rapid and increased with soil organic matter content. The coarsest soil size fractions (2000–200 and 200–50 μm) containing the nonhumified organic matter presented the highest capacity to form bound residues. No effect of tillage system was observed, probably because of the uniform sampling depth at 20 cm, hiding the stratification pattern of soil organic matter in nontilled soils.

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Copyright © 2003. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyASA, CSSA, SSSA