CHAINA, India — For two decades, Mahender Singh grew his vegetables without chemicals on his 10-acre plot of land in Pipal Mangoli, a village in southeastern Punjab. Then in 1967, an official from India’s Agriculture Department arrived in the nearby city of Patiala with a bag of chemical fertilizer, and farming in Punjab changed radically.

With the introduction of chemicals such as urea, phosphate and pesticides as well as new farming technologies and irrigation systems, this fertile northern Indian state quickly became the seat of the country’s agricultural revolution in the 1970s and 1980s. And farmers like Singh, now a vibrant 69-year-old with a snow white beard, started to see their harvests multiply.

But alongside this burst of prosperity came the harrowing side effects of pouring chemicals into the ground: People’s health deteriorated rapidly, as did water and soil quality, and neither the government nor consumers took action. In the past decade, however, farmers like Singh have taken matters into their own hands and returned to the chemical-free, organic farming practices they used before fertilizers showed up.

“I had confidence in my own method and my own labor,” he said. “I’m convinced that organic farming works.”

Singh is not alone in switching to organic. Punjab now has approximately 1,500 hectares of certified organic land, and India has emerged as a global leader in organic farming, with 600,000 certified producers. The countries with the second- and third-largest outputs are Uganda and Mexico, according to a report based on 2012 data, both of which have fewer than 200,000 organic producers.

Motivated by growing international demand, the Indian government has encouraged the shift toward organic. In 2004, India introduced the National Project on Organic Farming, and within 10 years the amount of certified organic land (land free of chemical residue) increased from 42,000 hectares to 4.72 million hectares.

At the beginning of 2013 the government launched a nationwide organic certification program to help India increase its organic exports. During the year, organic exports rose 7.73 percent, and the country produced 1.24 million metric tons of organic produce, according to an arm of the government responsible for overseeing agricultural development. India collected $403 million in revenue from these exports, out of a $63.8 billion global organic market.

While government interest in organic is largely market driven, for independent farmers in Punjab, the choice is about more than the economics; it’s about grappling with the legacy of the Green Revolution, an agricultural overhaul that began in the 1940s and reached the state more than 50 years ago.