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This article in JEQ

  1. Vol. 20 No. 4, p. 763-769
    Received: Dec 20, 1990

    * Corresponding author(s):
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Evaluation of Methods for Characterizing Carbofuran Hydrolysis in Soil

  1. T. B. Parkin *,
  2. D. R. Shelton and
  3. J. A. Robinson
  1. USDA-ARS-National Soil Tilth Lab., 2150 Pammel Dr., Ames, IA 50011;
    USDA-ARS-PDL, Bldg. 050, BARC-W, Beltsville, MD 20705;
    7922-190-MR, The Upjohn Co., Kalamazoo, MI 49001.



The objective of this study was to develop a method that could be applied to investigations of soil/environmental factors influencing the spatial and temporal variability of carbofuran hydrolysis in field soils. Two factors were considered: (i) soil handling and pesticide application, and (ii) the method of data summarization. Three soil handling/pesticide treatments were evaluated: (i) sieved soil/sprayed pesticide application, (ii) injected pesticide application/sieved soil, and (iii) injected pesticide application/intact core incubation. This last method was developed to mimic field conditions where high localized concentrations of carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) occur as a result of banded application of granular carbofuran at planting time. For all three treatments sigmoidal 14CO2 production kinetics were observed. Several mathematical models for describing sigmoidal product appearance data were evaluated and a general saturation model was found to yield the best fit. Using parameter estimates obtained from this model in statistical tests, we found that the intact core soil treatment yielded significantly longer half lives for carbofuran degradation. Additional experimental evidence suggests that soil structure of the intact cores retarded diffusion of the 14CO2 produced from carbofuran degradation and influenced the kinetic pattern observed.

Contribution from the USDA-AR and the Upjohn Company, Kalamazoo, MI.

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