Nutrient Cycling in Agroecosystems

, Volume 80, Issue 3, pp 211–222

Decomposition of Bt and Non-Bt Corn Hybrid Residues in the Field

  • David D. Tarkalson
  • Stephen D. Kachman
  • Johannes M. N. Knops
  • Janice E. Thies
  • Charles S. Wortmann
Research Article


Results of a previous laboratory study indicated that six transgenic crops expressing the Cry1Ab insecticidal protein from Bacillus thuringiensis (Bt) decomposed at a slower rate than their respective non-Bt isolines. Consequently, litter decomposition rates, nitrogen cycling, and carbon pools may change in agricultural systems as the result of the widespread use of Bt crops. In this study, we assessed the decomposition rates and chemical composition of commonly grown hybrids of Bt and non-Bt isolines of corn (Zea mays L.) in the field. Leaves, stalks, and cobs from two Bt corn hybrids (Pioneer 34N44 Bt and NC+ 4990 Bt) and their non-Bt isolines (Pioneer 34N43 and NC+ 4880) were analyzed for biomass fractions (soluble, hemicellulose, cellulose, and lignin) and total C and N content. Litterbags containing these residues were buried at a depth of 10 cm in a Holdrege silt loam (fine-silty, mixed, mesic Typic Argiustolls) soil and recovered 5, 11, 17, and 23 months after placement in the field. There were no differences in the rates of decomposition and mass of C remaining over time between the Bt and non-Bt corn residues. Plant parts differed in decomposition rates where leaves > stalks > cobs. There were differences in total C, total N, biomass fractions, and C:N ratios between initial Bt and non-Bt corn residues, and between companies (NC+ and Pioneer), however, these differences did not result in differences in their rates of decomposition or mass of C remaining over time. For each plant part, there were no differences in lignin content between the Bt and non-Bt residues. These data suggest that the Bt and non-Bt corn hybrids used in this study should not cause differences in carbon sequestration when their residues decompose under similar environmental conditions.


Decomposition Bt Corn Biomass Biomass fraction Lignin Soluble Cellulose Hemicellulose 



Ash free dry weight

Bt corn

Corn hybrid containing insecticidal proteins derived from the bacterium, Bacillus thuringiensis


Analysis of variance


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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • David D. Tarkalson
    • 1
  • Stephen D. Kachman
    • 2
  • Johannes M. N. Knops
    • 3
  • Janice E. Thies
    • 4
  • Charles S. Wortmann
    • 5
  1. 1.United States Department of AgricultureAgricultural Research Service, Northwest Irrigation and Soils Research LaboratoryKimberlyUSA
  2. 2.Department of StatisticsUniversity of Nebraska-LincolnLincolnUSA
  3. 3.School of Biological SciencesUniversity of Nebraska-LincolnLincolnUSA
  4. 4.Department of Crop and Soil SciencesCornell UniversityIthacaUSA
  5. 5.Department of Agronomy and HorticultureUniversity of Nebraska-LincolnLincolnNE

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