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[NEW DELHI] Genetic modification is credited with tripling cotton production in India, but a new analysis of 20 years of official data suggests otherwise.
 
Agrochemical giant Monsanto — which was recently acquired by the pharmaceutical company Bayer — introduced Bt cotton to India in 2002, and it now accounts for 90 per cent of cotton planting in the country. The variety was genetically modified by splicing in genes from the soil bacterium Bacillus thuringiensis (Bt), which produce toxins harmful to bollworm pests.
 
Since its introduction, multiple studies have reported increases in cotton yield and reduction in pesticide use. But NGOs and environmental activists have linked Bt cotton to growing fertiliser use, worsening farmer debt and even increasing the number of farmer suicides. Also, one of the two bollworm species that the variety was supposed to protect against quickly developed resistance to Bt toxins.
 
An analysis of 20 years of data from India’s ministry of agriculture now suggests yield increases were unrelated to Bt cotton’s introduction and is better explained by higher fertiliser use, better irrigation and the introduction of new pesticides. It also found that farmers now spend more on pesticides than before Bt cotton’s introduction.
 
“Major scientific journals declared Bt cotton to be a ‘winner’ for India even before Indian farmers began to adopt it,” said Glenn Stone, an anthropologist at Washington University in St. Louis in the US and co-author of the analysis, which was published 13 March in Nature Plants.
 
“But the first long-term study of Bt adoption and production trends at both national and state levels shows that Bt seeds were not the cause of rising yields and that the insecticide reductions were fleeting,” says Stone.

“The first long-term study of Bt adoption and production trends at both national and state levels shows that Bt seeds were not the cause of rising yields and that the insecticide reductions were fleeting”

Glenn Stone, Washington University

The authors compared data on the proportion of farmland dedicated to Bt cotton, cotton yields, fertiliser used per hectare and expenditure on insecticide from 1999 to 2018. They found yields were already increasing before the introduction of Bt Cotton and that one of the sharpest rises occurred in 2003, when Bt cotton accounted for less than five per cent of India’s crop.
 
Increasing yields correlated most closely with rising fertiliser use, the authors say, but also with the introduction of new insecticides between 2000 and 2002.
 
The analysis did find a significant drop in pesticide use between 2004 and 2012, which was attributed to Bt cotton’s introduction. But this was short-lived because the pink bollworm developed resistance and the widespread use of the crop meant the resistant population spread rapidly. Bt cotton has also proven vulnerable to other pests which, the researchers say, has pushed farmers to use even more pesticides than before.
 
However, Matin Qaim, an agricultural economist at the University of Goettingen in Germany who has studied Bt cotton in India, says the simple graphs the authors used to compare trends do not incorporate factors like weather or farmer education and that previous studies had better data and statistical approaches.
 
“They [study authors] draw far-reaching conclusions about causal effects from simple graphs,” Qaim said. “Our results clearly show that Bt cotton adoption significantly increased crop yields, farmers’ profits, and farm household living standards.”
 
The authors of the paper say, however, that almost all previous studies consider too short a period to make solid claims about the cause of yield increases or pesticide use.
 
They also say that their findings reflect a wider problem caused by the spread of non-native cotton hybrids in India. These varieties require far more fertiliser than native species, have worse resistance to Indian pests, and are not suited to the climate in most of the country, they say. Bt cotton is a hybrid, but non-Bt hybrids already accounted for 38 per cent of the crop before its introduction. According to the authors, farmers now spend more on pesticides than before the introduction of Bt cotton and the indications are that the situation will continue to deteriorate.
 
“India should shed its obsession with hybrid cotton, especially for 65 per cent of its area which is under rainfed and marginal input conditions which are unsuitable for hybrid cotton,” says co-author Keshav Kranthi from the International Cotton Advisory Committee in Washington DC and former director of India’s Central Institute for Cotton Research.
 
“Moving back to desi (native) cotton varieties, though slow, will be a great option for sustainable high yields through minimum chemical inputs,” Kranthi said.
 
Bayer declined to comment.
 
This piece was produced by SciDev.Net’s Asia & Pacific desk.

*A table previously included in the article was removed because it featured outdated information.