The very things that made the Green Revolution so stunning - that made the last doubling in agricultural productivity possible - now cause trouble. Efforts to improve agricultural productivity in the short-term are often designed to succeed at the expense of long-term sustainability, whether this takes the form of ecological stress, loss of genetic diversity in standing crops, salinization and alkalization of irrigated lands, nitrate pollution of ground-water, or pesticide residues in food.
Agricultural technology has created the possibility of specialisation and intensification, and policies have encouraged the adoption of these new technologies. Whilst this technological innovation has been successful - sometimes spectacularly so in terms of increasing output per hectare - this has not been without its cost. Wildlife populations have plummeted and high inputs of chemical fertilisers and pesticides have created health hazards in many aquifers. This can be viewed as a change from working within the natural constraints of the environment, to attempting to operate more independently of the local environment and relying instead on external inputs. As a result, many farming systems have been converting into something which is, actually or potentially, damaging to the environment.
The doubling of agricultural yields experienced earlier this century required an eightfold increase in the use of nitrogen fertilizers and thirtyfold increases in the application of potash and phosphorus. In some places, additional applications of fertilizer are no longer economically feasible because they produce only fractionally higher yields.
At the beginning of the 21st century, the states of Punjab and Haryana are on the edge of a grave environmental crisis. They were at the forefront of the Green Revolution in the late 1960s and early 1970s, in which farm machinery, pesticides and fertilizers, irrigation and the replacement of traditional crops with high-yielding varieties dramatically increased productivity. The two states together provide 80 percent of India's food supply. But the land is increasingly unable to support this burden of intensive agriculture. Crop yields and water resources are declining alarmingly, and some parts are close to becoming barren. Many farmers are heavily in debt from their investments in new equipment and reliance on chemicals, and rural unemployment is increasing. In the wheat belt of Ludhiana, Punjab, heavy use of fertilizer has caused excess nitrates to leach into the groundwater, posing hazards for human health. Without massive change towards more sustainable agriculture, say using less-intensively farmed sorghum and millet, there is little doubt that this food basket of India will collapse within a decade, placing the country's population at great risk of famine.