Since the 1960s, farmers in Punjab, India have practiced some of the most intensive broad scale grain production in the world. As a result, the state has earned the nickname “the food bowl of India” for its out sized role in adopting and implementing Green Revolution technologies that in the last decades of the 20th century helped end centuries of periodic famine in South Asia.
But the Green Revolution in Punjab came with a heavy price. Even as yields per acre shot up year after year, heavy use of pesticides, synthetic fertilizer and tube-irrigation soared as well, contributing to cancer, degrading the natural capital of the soil and–perhaps most importantly–depleting non-renewable underground aquifers at staggering speed. Now, even as agricultural productivity has plateaued, a dropping water table now puts the food security of the entire country at risk.
“Food security in India is largely associated with the food production of Punjab state,” says Rajinder Sidhu, professor of Agricultural Economy at Punjab Agricultural University, “So if anything goes wrong with the food production system of Punjab State, the food security of the country is endangered.”
Along with his colleague, Professor Kamal Vatta, Sidhu has been working in partnership with the Columbia Water Center to test and implement new water-saving techniques among Punjabi farmers. The project is sponsored by the PepsiCo Foundation.
Over-cultivation of rice is a chief culprit in the groundwater depletion crisis. While not a traditional crop in semi-arid Punjab, since the 1960s the combination of new bore well technologies and government policies subsidizing both the price of rice and free electricity for farmers has turned the state into a major exporter of the crop. Traditionally, rice production has been led to the flooding of rice fields so that the crop grows in standing water throughout much of the growing season.
Given that rice is likely to remain an important crop for the region into the foreseeable future, how can farmers use less water? Enter the tensiometer, a simple device that measures the amount of moisture in soil.
Tensiometers in one form or another have been around for decades, but commercially available devices were traditionally both expensive ($124 in a recent Internet search) and difficult for a poor, often uneducated farmer to install and read, in spite of potential water savings. A team survey of rice farmers in the region found that the vast majority had not heard of the technology, and only about 1 percent (9 out of 700 farmers surveyed) were using tensiometers to regulate water use.
To address this issue, soil scientists at the Punjab Agricultural University developed a simpler model of the device—one that had no moving parts and no numbers or text, only three bands, red, yellow and green to indicate when farmers should irrigate rice fields. The PAU’s tensiometer is made up of an inner and outer tube, a ceramic cup and a plug, and works on the principal of negative pressure; as soil moisture drops, the water level in the tube drops. When it drops below the green band into yellow, the farmer is asked to irrigate. The PAU’s version of the device costs only $6.
Early experimental results were promising, but until recently the devices had never been field-tested.
With the help of the Columbia Water Center, Professors Sidhu and Vatta last year recruited 525 farmers in 10 villages for the first large-scale field-test of the technology. In order to set the groundwork for later expansion, the team worked with village leaders and others to target progressive, early-adopter farmers who were likely to be looked upon as opinion-leaders in their community.
The team then installed the tensiometers in rice fields. In order to get accurate results, farmers were instructed to irrigate only one acre of their fields based on the tensiometer readings, and to use the other fields as control plots.
Initial results were remarkable. On average, farmers irrigated the tensiometer fields 30 to 35 percent less than on control plots—with no adverse impact on yield. In fact, anecdotal reports suggested that in some cases yield actually improved, as farmers were able to minimize some pest diseases associated with excessive standing water.
Asking so many farmers—whose livelihoods depend on a good yield—to manage a percentage of their crop differently was scary for them, says Professor Sidhu. But in the end, results bore out the field tests. “On the basis on that empirical research,” he says, “we now have the strength to say to farmers, ‘yes, you will save water, and yields will remain the same.’”
In fact, it is possible that future water savings could be even greater than first tests indicate, for two reasons. First, some farmers admitted to being influenced by tensiometer readings even when deciding when to irrigate their control plots. If true, it means that the official tensiometer plots were competing with control plots that were already being irrigated less than normal.
Second, 2010 was an unusually wet year in north-east India – as much as 30 percent wetter than average. It is possible that on a more typical dry year, tensiometers will save even more water.
Even so, by professor Vatta’s calculations, this year’s tensiometer trial saved as much as 167 million liters of water—about as much as 1.2 million people in India use in one day. Both Sidhu and Vatta are enthusiastic about the results, and believe that much wider adoption of the technology is only a matter of time.
“We also believe that the small—was invisible, actually,” says Vatta. “The farmers used to follow the thinking that ‘bigger is beautiful.’ But small is also beautiful. This small technology, when they saw it working, I think they couldn’t believe it was working. They were really amazed.”
Farmers, he said, are normally impressed with large machinery like laser-levels. “It’s a big machine, so you are fascinated. But that same result can be achieved with a tensiometer—something that’s just two feet in length.”
“It’s very cheap and can be accessed even by the poor farmer,” says Sidhu. “So that’s the beauty of this technology. To me because it is scale-neutral, the possibility of its adoption is much higher than those technologies that are not scale neutral.”
Next year the team plans recruit 5,000 farmers for the next part of the test. And while this year the CWC-PAU team provided the tensiometers for free, next year they hope to get the farmers and government to pay part of the cost. After all, says Sidhu, for $6, “it’s not a big expense, even for the poor farmers.”
Sometimes the small, cheap solutions really are the most beautiful.
To learn more about the Columbia Water Center/Punjab Agricultural University tensiometer project, watch an interview with Kamal Vatta and Rajinder Sidhu on Youtube.