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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY-BASED SOIL AND CROP MANAGEMENT SYSTEMS FOR SUSTAINABLE AGRICULTURE

Location: North Central Agricultural Research Laboratory

Title: No Differences in Decomposition Rates observed between Bacillus thuringiensis and Non-Bacillus thuringiensis Corn Residue Incubated in the Field

Authors
item Lehman, R
item Osborne, Shannon
item Rosentrater, Kurt

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 6, 2007
Publication Date: January 11, 2008
Citation: Lehman, R.M., Osborne, S.L., Rosentrater, K.A. 2008. No Differences in Decomposition Rates observed between Bacillus thuringiensis and Non-Bacillus thuringiensis Corn Residue Incubated in the Field. Published online 11 January 2008; doi:10.2134/agrojnl2007.0123. Agron J 2008 100:163-168.

Interpretive Summary: Recent speculation of slower residue decomposition for Bt corn hybrids compared to non-Bt corn hybrids has prompted investigative study. We evaluated the residue decomposition rates of Bt and non-Bt corn hybrids over a period of 22 months (November 2004 – September 2006) under field conditions using the litter bag technique. Measurements of decomposition of corn residue under field conditions showed no differences between Bt and non-Bt corn hybrids. No differences in compositional properties, including lignin content, were observed among the four hybrids. Physical compression testing of residue mechanical strength properties showed potential differences among the hybrids. This is the first report regarding decomposition of Bt corn residue under field conditions following ambiguous reports from laboratory studies on the relative susceptibility of Bt corn residue to decomposition. As yet, insufficient data exists to explain the perceived resistance of some GM corn residues to decay or the apparently escalating amounts of persistent corn residue that have stimulated more aggressive tillage.

Technical Abstract: Recent speculation of slower residue decomposition for Bt corn hybrids compared to non-Bt corn hybrids has prompted investigative study. We evaluated the residue decomposition rates of Bt and non-Bt corn hybrids over a period of 22 months under field conditions using the litter bag technique. The four corn hybrids used were (i) DKC60-16 (Bt+, Cry1Ab protein active against the leptidopteran European corn borer, event MON810), (ii) DKC60-12 (Bt+, Cry3Bb1 protein active against the coleopteran corn rootworm, event MON863), (iii) DKC60-14 (stacked Bt++, Cry1Ab and Cry3Bb1 proteins) and, (iv) DKC60-15 (Bt-, base genetics). The biochemical and physical properties of the corn residues were determined. No differences in the decomposition rates of the residue from the four corn hybrids were detected. Residue decomposition rate constants were approximately -0.25 day-1 for all four hybrids with predicted residue half-lives of about 200 days. No differences in compositional properties, including lignin content, were observed among the four hybrids. Physical compression testing of the chopped residue failed to detect significant differences in mechanical strength properties among the hybrids. This is the first report regarding decomposition of Bt corn residue under field conditions following ambiguous reports from laboratory studies on the relative susceptibility of Bt corn residue to decomposition.

Last Modified: 7/28/2014