Long-term impact of Bt cotton: An empirical evidence from North India

摘要

Bt (Bacillus thuringiensis) cotton has been commercially grown in India for the past 19 years. Genetic Engineering Approval Committee (GEAC) approved the release of Bt cotton for commercial cultivation in 2002 in western and southern parts of the country. In Punjab, Bt cotton was released for cultivation in 2005. Before the release, Bt cotton was adopted by 72% farmers on 22% of the total cotton area. However, a lot of questions have been raised recently on the impacts of Bt cotton. To find out the long-term socio-economic and environmental impacts of Bt cotton cultivation on cleaner production, we revisited cotton growers surveyed in 2003 and 2004. Before-after, with-without, and difference-in-differences (with and without sample attrition) within farm comparisons were analyzed to find the impact of Bt cotton over time. Our results show that sucking insect pests have replaced bollworms as the key pests. There has been a steep decline in insecticide applications to control bollworms, the target pest of Bt cotton, by 97%; however, this has been offset by an increase in the insecticide application by 154% to control sucking pests. Moreover, the increase in pesticide use was driven by the use of fungicides, which were not applied in cotton earlier, and increased use of herbicides. Our results show overall positive impact of Bt cotton on volume of insecticide active ingredients (a.i.) applied, insecticide applications, use of highly hazardous and riskiest insecticides, and resultant environmental impact of the field use of insecticides on cotton. Yields have stabilized after the commercialization of Bt cotton.