Original Paper

Biology and Fertility of Soils

, Volume 48, Issue 3, pp 315-324

First online:

Effects of conventionally bred and Bacillus thuringiensis (Bt) maize varieties on soil microbial biomass and activity

  • Andreas FließbachAffiliated withResearch Institute of Organic Agriculture Email author 
  • , Monika MessmerAffiliated withResearch Institute of Organic Agriculture
  • , Bruno NietlispachAffiliated withResearch Institute of Organic Agriculture
  • , Valentina InfanteAffiliated withResearch Institute of Organic AgricultureFacultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile
  • , Paul MäderAffiliated withResearch Institute of Organic Agriculture

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Genetically modified (GM) maize containing genes from the soil bacterium Bacillus thuringiensis (Bt) was cultivated on 29% of the total maize production area worldwide in 2009. Most studies to date compare Bt-maize varieties with their near isogenic lines; however, there is little information on the variability of conventional maize breeding lines and how the effects of Bt varieties are ranked within. In our study on the potential risks of Bt-maize varieties, we analyzed tissue quality and compared the effects of ten conventional and GM maize varieties on soil microbiological properties in a replicated climate chamber experiment. All maize varieties were cultivated twice in the same soil microcosm. Shoot yields and soluble C in leaf tissue of Bt varieties were higher than the ones of non-Bt. Soil dehydrogenase activity was reduced by 5% under Bt varieties compared to non-Bt, while most of the other soil microbial properties (soil microbial biomass, basal respiration) showed no significant differences between Bt and non-Bt varieties. The leaves and roots of one Bt variety were decomposed to a greater extent than the ones of its near isogenic line; the conventional breeding lines also showed higher values. Changes in crop and soil parameters were found when comparing the first and the second crops, but the effects of repeated cropping were the same for all tested varieties. For the studied parameters, the variation among non-Bt-maize varieties was similar to the difference between Bt and non-Bt varieties.


Bt-maize Soil fertility Cry1Ab GMO Microbial biomass Soil respiration Dehydrogenase Mycorrhiza