Crossbow's eKo system has triggered an agricultural revolution in the world of precision agriculture and environmental monitoring. This cutting edge system was recently featured in the San Francisco Chronicle and the story can be viewed here.

(08-31) 15:50 PDT -- On a rolling hillside planted with row upon row of Cabernet grapes, viticulturist Jason Cole waxes eloquent about the elusive notion of 'terroir,' a term French farmers use to describe the 'je ne sais quoi' of crops harvested in any given locale.

"Grapes, chocolates, coffee, these are all incredibly good at soaking up their environments and spitting them out in their fruits," said Cole, who oversees the preening and pampering of more than 500 acres of vines planted at the Stagecoach Vineyard in Napa County.

That vineyard is a test bed for a new wireless sensing technology that measures soil wetness, wind speed, temperature and humidity to take the statistical pulse of the vineyard's microclimates to help determine how often and how much to irrigate. The system being tested at Stagecoach was developed by Crossbow Technology, a privately held, 90-person San Jose company that has created inertial guidance sensors for the aviation industry and researched the use of wireless sensor networks for the federal Defense Advanced Research Projects Agency. Other manufacturers of microclimate sensing systems include the Austrian company Adcon Telemetry, as well as Ranch Systems of Novato and Grape Networks of San Ramon.

The sensors that Cole is using at Stagecoach Vineyard represent one manifestation of a broader phenomenon called precision agriculture - the attempt to tailor the cultivation of large stretches of land so that the smallest possible subsection of a farm gets special but automated attention. In the Midwest, with its amber waves of grain, precision agriculture has been synonymous with huge tractors equipped with global positioning systems to keep the rows straight, for instance. But in California, the land of fruits, nuts and other specialty crops, precision agriculture has been expressed in technologies such as Cole's efforts to use wireless sensors to compute 'terroir.'

"The way that growers for many years decided whether it was time to water was they stuck their thumb in the ground," said Robert Robinson, vice president for Crossbow's wireless sensor division.

The basic field kit that Crossbow released earlier this year, priced at $3,359, consists of three sensing nodes that feed data collected in the field through an electronic gateway into what is essentially a Web page that can be viewed from any Internet-connected device. Crossbow says that basic configuration can divine the microclimate of sites as varied as a 4-acre plot of land in hilly and varied terrains such as Napa and 20 acres in the flatter, homogeneous Central Valley. Additional kits can extend the sensing network, wirelessly and indefinitely, over hill and dale.

Moisture sensors
Kneeling alongside a vine at Stagecoach Vineyard, Cole explained how the system, in addition to measuring temperature and humidity with above-ground sensors, sticks a virtual thumb deep into the soil in the form of two moisture sensors, one at a depth of 1 foot and the other at 3 feet.



"The whole point is to monitor what the roots are experiencing," Cole said. "Watering grapes is one of the most important factors to wine quality. You want to stress the vines in order to condense the flavor into smaller berries."

UC Davis Professor Stu Pettygrove, a soil specialist who has tracked precision agriculture in California, said the water-sensitivity of wine grapes, coupled with their high value relative to other agriculture products, make them a good candidate for this high-tech approach. But how many other California crops fit that description? Pistachios were the only other example Pettygrove offered. He said water-stinginess at just the right point helps burst the shells, making pistachios easy to eat.

Tree crops experiment
Professor Michael Delwiche, chairman of biological and cultural engineering at UC Davis, has experimented with wireless sensing systems that precisely apply water - sometimes mixed with chemical fertilizers in a process called fertigation - to tree crops like nectarines. So far, however, the cost benefit is not there in production orchards, he said.

Delwiche said wireless sensing systems and precision watering might find a home in commercial nurseries and flower-growing greenhouses, where the impetus is not purely economic - as measured by greater crop value - so much as it is regulatory. "They are under environmental regulation not to have runoff from the nursery location," Delwiche said. Eventually, manufacturers will try to improve the performance and bring down costs to encourage broader adoption of wireless sensing systems, he said. Meanwhile, the technology remains economical in niche markets - or exceptionally arid locales.

"In Israel, where water is so dear and they have the technological infrastructure, they're doing a lot of work in this area," Delwiche said. But at Stagecoach Vineyard, where cachet is central to the business plan, the cost of wireless sensing technology is hardly a barrier to the pursuit of quality.

"We're trying to grasp the 'terroir', but you'll always be grasping, you'll never have it all," Cole said.

For more information on the eKo system, visit the eKo site here.

The picture of a future with wireless sensor networks-webs of sensory devices that function without a central infrastructure--is quickly coming into sharper focus through the work of Los Alamos National Laboratory computer scientist Sami Ayyorgun. Using Crossbow's TelosB Motes in their research, proponents of this new technology see a world with deployments to improve a wide range of operations.

Engineers could wirelessly monitor miles of gas and oil pipelines stretching across arid land for ruptures, damage, and tampering. Rescue workers might detect signs of life under the rubble of a collapsed building after an earthquake, thanks to a network of sensors inside the structure. Armed forces could keep an eye on a combat zone or a vast international border via a sensor network that could promptly provide alerts of any intrusion or illicit trafficking.

"It's not easy to envision the impacts that sensor networks will make, both socially and economically," Ayyorgun said. "Like many other researchers, I think they are likely to rival the impact that the Internet has made on our lives."

Ayyrogun has developed a new communication scheme that brings the reality of these and other applications a step closer. He has shown for the first time that concurrent gains in many measures of performance are possible, including connectivity, energy, delay, throughput, system longevity, coverage, and security.

In recognition of the multifaceted improvements Ayyorgun's research makes on state-of-the-art technology in this field, his recent paper, "Towards a Self-organizing Stochastic-Communications Paradigm for Wireless Ad-hoc/Sensor Networks," has been nominated for the Best-Paper Award from a pool of more than 250 manuscripts at the International Conference on Mobile Ad-hoc and Sensor Systems (MASS) of the Institute of Electrical and Electronics Engineers (IEEE). Ayyorgun will present the paper at this prestigious meeting of the IEEE beginning September 29, in Atlanta, Georgia.

Like cell phones, wireless sensor networks depend on small, independently powered devices, often called motes, to communicate. But unlike cell phones, which always relay their signal through a base station such as a tower, multihop sensor motes use each other to relay signals, transmitting communiqués through a series of "hops" from one mote to the next. Without the need to build a mesh of base stations that must be wired or have a substantial supply of energy, creating information-bearing ad-hoc networks to suit each unique set of circumstances would significantly reduce costs.

"Wiring or 'beefing up' system resources is expensive and is often not feasible for many applications," Ayyorgun said, calling that a "major impetus" for wireless network research. But with nearly all motes dependent on a portable source of power like a battery, it is important that the devices be as energy efficient as possible. "Energy efficiency is a first-class design criterion," he said.

And energy utilization isn't the only consideration. Other performance aspects of concern include the system's connectivity; the delay, or time it takes for data to be transported; the throughput, which measures the amount of data the system can handle at once; and network security, to name a few. Many solutions aimed at advancing wireless sensor networks have managed to improve performance over at most a few metrics at the expense of others. Ayyorgun analogizes the conundrum to a Rubik's cube, the cube-shaped toy in which the aim is to match each of the six sides with one distinct color. Often, gains in one aspect of wireless sensor network performance such as energy efficiency have only been achieved with losses in another area, such as the end-to-end delay.

With Ayyorgun's scheme, however, "all of the colors have started to match," he said. The sensor network was more energy efficient with shorter delay times, and the other performance considerations mentioned earlier have all improved as well.  "The motes communicate randomly, but their random behavior-their genetic code, if you will-has collective intelligence by design," he said. That collective intelligence results in the concurrent performance gains over many aspects, he added.

"We have good colors on all sides, but it's not perfect yet," Ayyorgun said, emphasizing that wireless sensor networks are still in the development stage. Many issues remain to be addressed, just as we are beginning to realize the potential of these "networks of the future."

Ayyorgun acknowledges the support of the Laboratory Directed Research and Development Office at Los Alamos, the Los Alamos Engineering Institute, the Center for Nonlinear Studies, and colleagues, as well as his students.

Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and Washington Group International for the Department of Energy's National Nuclear Security Administration.

Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.