Simultaneous Stimulation of Soil Respiration and Plant Biomass in Transgenic Bacillus thuringiensis Crop Cultivation

Abstract Aims Transgenic Bacillus thuringiensis (Bt) crops are cultivated globally to mitigate potential pest crisis and reduce insecticide dependence. However, the response of belowground system to Bt crop cultivation remains controversial, limiting our understanding of Bt crops’ role in agriculture sustainability. The aim of this study was to assess Bt crops’ influence on soil system, including variables of soil respiration, soil carbon and nutrient pools and soil biodiversity. Methods We conducted a global meta-analysis of 88 experimental studies to assess the influence of Bt crop cultivation on soil system. Results Bt crops significantly increased soil respiration by 6.0% (p < 0.05), alongside a 14.3% rise in aboveground biomass and a 4.3% belowground plant biomass. Bt crops reduced rhizospheric soil organic carbon (SOC) by 3.4% but increased bulk soil SOC by 3.1%. SOC, nematode diversity, and fungal diversity accounted for 50%, 34%, and 30% of the variation in soil respiration under Bt crop cultivation, respectively. The decrease of microbial competition for nitrogen under Bt crop cultivation caused a significant reduction in microbial biomass carbon: nitrogen ratio. Conclusions Under Bt crop cultivation, the increased soil respiration might be caused by the stimulated microbe nutrient mining due to plant production-induced system nitrogen deficiency, especially in rhizosphere. Dispite their advantages in biomass accumulation, long-term cultivation of Bt crops may pose ecological risks on soil fertility sustainability and introduce uncertainties in agricultural life cycle assessments.