A new study directly links the crisis of suicides among Indian farmers to Bt cotton adoption in rain-fed areas, where most of India’s cotton is grown. Many fall into a cycle of debt from the purchase of expensive, commercialised GM seeds and chemical inputs that then fail to yield enough to sustain farmers’ livelihoods (see [1] Farmer Suicides and Bt Cotton Nightmare Unfolding in India, SiS 45).

Rain-fed cotton yield dependent on weather not pest attacks, Bt technology futile

Using physiologically based demographic modelling (PBDM) methods to assess the dynamics of weather and pests on cotton yield, this latest study led by Professor Andrew Gutierrez at University of California, Berkeley [2] calls into question the relevancy of Bt cotton, considering that the main target of the Bt cotton, the pink bollworm, only attacks irrigated but not rain-fed cotton.

The PBDM method, unlike previous studies that focus on econometric analysis of Bt cotton yields, looks at the holistic biological and ecological underpinnings of crop yield. Using it to simulate prospective yields of rain-fed non-Bt cotton from 1980 to 2010 and its relationship to pink bollworm dynamics, the model provides a historical baseline measurement of the Indian cotton situation prior to the 1970s green revolution, where pink bollworm was the major pest of Indian cotton. Since the 1970s, insecticide technology has led to ecological destruction including outbreaks of formerly secondary pests, insecticide resistance and damage to human health. This was followed by Bt technology that has also had negative effects on Indian cotton agriculture.  

Inputting parameters on cotton growth from field experiments in India, the researchers estimated the daily effects of water stress on cotton phenology, growth and yield formation, predicting the daily growth dynamic of leaves, stems and roots as well as fruit and yield across 4 states (Maharashtra, Karnataka, Gujarat and Andhra Padresh) where most of the suicides are occurring. The model was then run using daily weather conditions (from the Climate Forecast System Re-analysis of the United States for Environmental Prediction). Pink bollworm dynamics were modelled by capturing the phenology of dormancy induction as regulated by increased temperature and photoperiod, and spring emergence from diapause as a function of temperature.

The results show that rain-fed cotton’s protection from pink bollworm arises from the timing of their fruiting season. Irrigated cotton has two fruiting cycles in a season, which is synchronised to pink bollworm emergence from diapause and development of the next generation larvae, while rain-fed cotton only has one cycle per season, fruiting only after the new adult bollworms have emerged (Figure 1). This makes Bt technology irrelevant for rain-fed cotton.

Figure 1   Simulated phenology of pink bollworm on irrigated and rain-fed cotton

Instead, the timing, distribution and quantity of monsoon rains is the main determinant of yield; as well as other factors such as planting density and mean daily temperature. As shown in Figure 2, rainfall in Yaratval, Maharashtra correlates with yield. These results led the authors to conclude that in low yield areas with high variability, Bt cotton does not provide assurances for yield of rain-fed cotton. And, short season non-Bt cotton is a viable option for both irrigated and rain-fed areas.

Figure 2   Simulated yields of rain-fed non-Bt cotton in Yavatmal, Maharashtra, during 1980-2010; top, yields follow rainfall and degree days > 12 ˚C, the base temperature above which cotton grows; bottom, linear regression analysis showing correlation between rainfall and yield

Bt cotton does not reduce insecticide use, increases cost burden

Bt crops were introduced to India in 2002 and by 2012 there were more than 1128 Bt hybrid varieties grown on 92 % of cotton growing areas [3, 4]. They are promoted on the basis of reducing pesticide use but despite initial declines, insecticide use in 2013 reached 2000 levels while yields have plateaued nationally and farmer suicides increased in some areas [5].  Industry has also promoted the use of insecticides and farmers, in order to avoid crop failure, likely applied increasing quantities of pesticides that do not boost yields but may instead increase ecological disruption and risk of crop failure. Industry has exploited this information gap to sell their Bt crops and insecticides. With the sustained use of insecticides added on to the costs of expensive Bt cotton seeds, farmers have been pushed into further economic distress.

Computing the average profits per hectare in rain-fed cotton (revenues from sale of seed cotton minus average costs of seed, insecticide and other production costs) the study highlights the drastic increases in costs now faced by farmers (see Figure 3). Prior to hybrid varieties, costs were nil to low (0-9 rupees per kg), but as fertile local varieties became unavailable, farmers increasingly bought F1 hybrid seeds that for Bt varieties cost an average 2111 rupees per kg. The average yields in the 4 states studied ranged from 300 – 1 200 kg per hectare, with low yields in Andhra Pradesh and Karnataka, and roughly half of the total area studied across the four states averaging less than 5 000 kg of lint cotton per hectare. Production costs rise from 8 % of total revenues for those averaging yields of 1 320 kg ha-1 to 21.1 % for those averaging 500 kg ha-1, resulting in a net daily income of less than 2 US dollars a day. For farmers getting only 300 kg ha-1, production costs increase to 42.2 % of total revenues, resulting in only 1 dollar a day of net income. Costs as a proportion of revenue decrease exponentially with yield. These data show that low yields and high variability are substantial sources of risk, exacerbated by the high costs of Bt cotton seed and continued use of insecticide.

Figure 3   Cotton yields, revenues and costs in rain-fed cotton areas