Impact of Bt Cotton on Punjab Soils

One of the least understood areas in the environmental risk assessment of genetically modified crops is their impact on soil and plant-associated microbial communities. In a review of literature, Dunfield and Germida (2004) found that transgenic plants and plant litter can influence the composition of the plant-associated microbial communities. Their review also points to such effects having been shown in a variety of plants with different transgenes. However, these effects are dependent on field site, seasonal variation, and method of analysis used to assess the community. They conclude by saying that changes in microbial communities associated with growing transgenic crops are relatively variable and transient in comparison with some other well-accepted agricultural practices. Even other scientists who reported that no conclusive research is present to conclude that significant direct effects on soil are present with transgenic crops also reiterate that a comprehensive evaluation of environmental impacts of GM crops grown under a wide range of soil properties is sorely missing.