Effects of transgenic Bt cotton on soil fertility and biology under field conditions in subtropical inceptisol

• Published in: Environmental monitoring and assessment 2013, Vol.185 (1), p.485-495
• Main Authors: Singh, Raman Jeet, Ahlawat, I. P. S., Singh, Surender
• Format: Article
• Language: English
• Subjects: Agricultural biotechnology; Agricultural practices; Agricultural research; Agriculture; Agronomy; Agronomy. Soil science and plant productions; Animal manures; Animal, plant and microbial ecology; Applied ecology; Arachis hypogaea; Atmospheric Protection/Air Quality Control/Air Pollution; Bacillus thuringiensis - genetics; Bacterial Proteins - genetics; Biological activity; Biological and medical sciences; Climate; Conservation, protection and management of environment and wildlife; Cotton; Cover crops; Crops; Dehydrogenase; Dehydrogenases; Dry matter; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Environmental monitoring; Enzymatic activity; Enzymes; Experiments; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Genetic engineering applications; Genetics and breeding of economic plants; Gossypium - genetics; Gossypium - growth & development; Legumes; Microbial activity; Mineralization; Monitoring/Environmental Analysis; Nitrogen; Peanuts; Pest Control, Biological - methods; Plant breeding: fundamental aspects and methodology; Plants, Genetically Modified - growth & development; Population; Productivity; Research centers; Soil - chemistry; Soil contaminants; Soil environment; Soil fertility; Soil Microbiology; Soil sciences; Soil testing; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Soils; Statistical analysis; Toxins; Urea; Use of agricultural and forest wastes. Biomass use, bioconversion; Water conservation
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-012-2569-1

Although there is large-scale adoption of Bt cotton by the farmers because of immediate financial gain, there is concern that Bt crops release Bt toxins into the soil environment which reduces soil chemical and biological activities. However, the majorities of such studies were mainly performed under pot experiments, relatively little research has examined the direct and indirect effects of associated cover crop of peanut with fertilization by combined application of organic and inorganic sources of nitrogen under field conditions. We compared soil chemical and biological parameters of Bt cotton with pure crop of peanut to arrive on a valid conclusion. Significantly higher dehydrogenase enzyme activity and KMnO 4 -N content of soil were observed in Bt cotton with cover crop of peanut over pure Bt cotton followed by pure peanut at all the crop growth stages. However, higher microbial population was maintained by pure peanut over intercropped Bt cotton, but these differences were related to the presence of high amount of KMnO 4 -N content of soil. By growing cover crop of peanut between Bt cotton rows, bacteria, fungi, and actinomycetes population increased by 60%, 14%, and 10%, respectively, over Bt cotton alone. Bt cotton fertilized by combined application of urea and farm yard manure (FYM) maintained higher dehydrogenase enzyme activity, KMnO 4 -N content of soil and microbial population over urea alone. Significant positive correlations were observed for dry matter accumulation, dehydrogenase enzyme activity, KMnO 4 -N content, and microbial population of soil of Bt cotton, which indicates no harmful effects of Bt cotton on soil biological parameters and associated cover crop. Our results suggest that inclusion of cover crop of peanut and FYM in Bt cotton enhanced soil chemical and biological parameters which can mask any negative effect of the Bt toxin on microbial activity and thus on enzymatic activities.