Two techniques show promise for helping farmers conserve scarce water in Punjab, India’s breadbasket.
India is running out of water for crops. Most of the water-intensive agriculture in the nation takes place in Punjab, a state in the northwest that makes up 2 percent of the country’s territory but provides more than 50 percent of its grain reserves. Farmers there currently pump out 45 percent more groundwater than is replenished by monsoon rains.
The problem has arisen in part because Punjabi farmers have veered away from growing traditional crops that are suited for semiarid land, such as wheat and corn, and turned instead to more profitable, but water-intensive, rice. “If Punjab is to continue as the food grain capital of India, modern agricultural practices will have to take into account the water situation and create a feasible long-range plan for a sustainable future,” says Shama Perveen, an associate research scientist at Columbia University’s Water Center, who has been working in the region. She and several colleagues from Columbia, in collaboration with Indian agriculture scientists, are testing a piece of that plan: two conservation tools that could help farmers use less water, even if it won’t alter their choice of crops.
One such tool is the tensiometer: a porous, ceramic bulb attached to a color-coded meter that reflects the moisture content of soil. In a preliminary experiment involving more than 500 farmers in 50 Punjab villages, the group handed out tensiometers, which were stuck into fields, including rice paddies. Farmers were told to irrigate the land only when the instruments showed that the moisture content was falling. Those who followed that guideline consumed nearly 30 percent less water than before.
The other technique relies on lasers that detect undulations in fields. Informed by the laser scans, farmers can level out any detected bumps before sowing, to help prevent puddles and dry patches and allow for more uniform irrigation. Laser leveling can save up to 20 percent of water usage, says Kapil Narula, head of the Columbia Water Center’s India operations.
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