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sábado, 14 de julho de 2012

Nanotech Goes Country: MEMS Chips To Measure Water Stress Down On The Farm

Rolling irrigation equipment over a thirsty late June cornfield in Irwin County, south central Georgia. Georgia has been particularly hard hit by drought over the last several years and farmers in the area have had to increasingly rely on irrigation to salvage their crops. Credit: Cynthia Griffin
Bruce Dorminey, Contributor
If the Fourth finds you with California Chardonnay in one hand and Sweet Georgia Corn in the other, then take a moment to reflect on just how much of your Independence Day feast is dependent on irrigation.
In this age of dwindling water resources, it’s a subject that Alan Lakso, a Cornell University crop physiologist, considers almost daily.
Conserving water is critical and will become more so,” said Lakso. “In the past 40 years or so, the greatest improvement in irrigation efficiency has been use of drip irrigation, but since then it has not improved greatly. In many ways, that’s due to the lack of methods to monitor water potential; the actual stress due to drying in soils and plants.
And with climate change scenarios predicting that most regions of the country are only getting hotter and drier, the plan is to become a lot smarter about when and how we irrigate.
Enter Lakso and colleague Abe Stroock, a Cornell Microfluidics engineer, who have jointly developed an electronic, MEMS (microelectromechanical systems) device to measure water stress potential. The basic concept has been used for years in a soil instrument called a tensiometer. But with MEMS technology promises a reasonably-priced, continuous water stress measurement, with a range some 100 times that of a classic tensiometer.
“We’re also hoping these devices could be manufactured for under $10 per unit,” said Lakso. “Initial lab testing looks very promising and a patent for the technology has been submitted, but it still needs field testing.”
The device works via Microfluidics, with each sensor containing a nano-sized water-filled tube. As the measured material (soil or plant tissue around the sensor) dries out with water stress, says Lakso, it will try and pull water out of the sensor. This, in turn, sets up a tension that is measured by the device’s pressure transducer which emits a voltage signal that would be picked up by a data logger or a wireless network.
At only about 3×5 millimeters in rectangular surface area, Lakso says as many as 10 of these MEMS devices would fit on an average-sized postage stamp. Dozens could be spread around any given field, or even embedded directly in a vine or tree’s trunk.
“The grower would go online and call up a color-coded, contour water stress map of the field,” said Lakso. “Growers aren’t used to getting that much data so the data handling is going to be an important component so we have been working with IT companies about how this data might be handled.”
An irrigation system hooked to a wireless network reading the field in real time, says Lakso, would see where the stresses are and turn on the field’s irrigation. Because the chip is water-proofed, a given MEMS network would not be ruined by irrigation and may even continue providing useful data for years. In the wine industry, however, sometimes the best quality grapes need moderate water stress in the middle of the season. But as Lakso notes, managing that fine balance requires precise water stress measurement.
A vineyard with a drip irrigation system runni...
A vineyard with a drip irrigation system running along the bottom of the vines (Photo credit: Wikipedia)
Because grape vines and trees have large root systems, Lakso says it would be better to monitor the plant itself. Thus, just because the soil surrounding the vine or tree may look barren, the plant may be completely healthy due to its ability to tap into water twenty to thirty feet down.
This [technology] will allow us to grow higher quality grapes and wines by optimizing vineyard irrigation regimes,” said Nick Dokoozlian, Vice President — Viticulture, Chemistry and Enology at E&J Gallo Winery, adding that he would expect the winery to implement the technology as soon as it’s commercially available. Lakso says other wineries are also interested.
But for traditional row crops, a MEMS system’s priority would simply be to keep the plants stress-free. And while such technology would surely save water, as Georgia Peanut Commission Chairman Armond Morris points out, they would also save farmers from high irrigation-related energy charges.
“A big portion of crop irrigation systems now run on electricity, but we also still have a lot of diesel units running irrigation engines and well [pumps],” said Morris.
A prototype water stress sensor on a US nickel. The prototype is larger than the final size which is approximated by the black lines. Credit: Alan Lakso
Although Georgia leads the nation in peanut production, with as many as 1.3 million tons of raw nuts projected to be harvested this year alone, such high yields are still heavily irrigation-dependent.
“Georgia is not as far behind in precipitation as in previous years,” said Morris. But he notes that the state’s water tables remain low, with irrigation use still well ahead of rainfall.
And while peanuts can tolerate dry periods, says Morris, irrigation is still crucial 70 to 90 days into the growing season when the plants are developing their nuts.
This [MEMS device] would mean that we could conserve water by irrigating at the time the crop needs it,” said Morris. “This is a great step in the right direction.”
Fonte: Forbes