Submitted to: Minnesota Academy of Science Meeting
Publication Type: Proceedings
Publication Acceptance Date: 4/25/2003
Publication Date: 4/25/2003
Citation: RUTHER, N.R., BARBOUR, N.W., JOHNSON, J.M. DECOMPOSITION AND COMPOSITION ANALYSIS OF SIBLING BT CORN AND NON BT CORN. CD-ROM. ST. PAUL, MN: MINNESOTA ACADEMY OF SCIENCE. 2003. Interpretive Summary:
Technical Abstract: Literature suggested that Bt corn has higher lignin concentration compared to its sibling non-Bt corn. It was hypothesized that an increase in lignin concentration would result in a decrease in the rate Bt corn decomposed compared to its non-Bt sibling. Reduced decomposition may result in increased residue, which could reduce erosion. However, persistence of Bt corn in the soil may also mean an increase in residence time of toxin, increasing potential hazard to non-target organisms and increasing selection potential for toxin-resistant target insects. This study determined the biochemical composition (soluble sugars, starch, hemicellulose, cellulose, lignin, total C and total N) and the rate of decomposition of stover from Bt and non-Bt corn on stover (2 mm). The ground stover was incubated in a Barnes soil at 25 deg C and 60% WFPS. Gas chromatograph was used to measure the total respired CO2 of amended soil periodically over 120 d. A two-component exponential decay model was used to describe the decomposition of the corn residue. The more quickly decomposing material is referred to as the active fraction and the slower component as the passive fraction. The half-life of the active component was about 11 d for both Bt corn and the non-Bt sibling. The passive component had a half-life of 1070 d for Bt corn and 1370 d for the non-Bt corn. This suggests that the Bt corn may decay slightly faster than the non-Bt corn. In the field, corn stover would be subjected to predation by macro and meso-fauna, which could alter the rate of decomposition.