The Wireless Vineyard: A Former Intel Researcher Reinvents Irrigation in the Mountains Above Napa
The vines are standing in straight rows along the irrigation pipes at Camalie Vineyards, high on the side of Mt. Veeder, in Napa Valley. For each vine a smaller pipe, thinner than a soda straw, runs from the pipe into the earth and down to the roots.
Here and there you can spot some yellow containers just on top of the vines. They are the nodes in a wireless sensor network, which among other things monitors the irrigation system and the soil moisture, and relays the information to a computer with a Web interface.
“The Internet has taken root in the environment,” says Mark Holler, owner of Camalie Vineyards and founder of Camalie Networks, the startup that developed the sensors plugged into the yellow containers and the software that runs them. The nodes themselvess and their communications and networking technology come from San Jose-based Crossbow, which was acquired by Memsic of Andover, MA, early this year.
The climate here is semi-arid. This means that that the harvest per acre is far lower than in the floor of the valley. And water for irrigation can be a big part of the cost of growing grapes. Some of the water comes from the vineyard’s own well, but at the end of the season Holler usually buys water that is driven up in tanks from the valley.
On the other hand, this means that the vines can produce a higher-quality grape that fetches a much higher price. The wineries pay about $100 per ton for “ordinary” Napa grapes, but Holler, the former technical director of neural network research at Intel, can get $6000 per ton for his Cabernet Sauvignon grapes. In other words, the harvest from Camalie is worth a great deal, even though vineyard is quite small—just about 4.4 acres—and the annual harvest only around 12 tons in total.
To get grapes of this really high quality, the wines have to be kept a bit thirsty. In the science of viticulture, this is defined as a certain level of “leaf water potential.” At the same time, if the vines get too thirsty—if their leaf water potential is too low—the plant will wilt.
This is where the yellow containers come into play. Each container is a node in the sensor network, with a wireless transmitter, a solar cell, a battery, and interfaces for up to four different sensors. The network is self-organizing; hook up the sensors you want and the nodes in the network will figure out how to transmit the data to your gateway computer. If a node breaks or loses contact, the rest of the network will adapt.
There are sensors that keep track of the water pressure in the irrigation system and sensors for wind, humidity and temperature. And most important of all, sensors measuring the “soil water tension”, which can be described as how hard the plant’s roots have to suck to draw moisture from the earth.
The soil moisture tension corresponds to the leaf water potential. (The drier the earth, the thirstier the plants.) The sensor measurements give Holler a way to keep his vines at just the right level of thirstiness, without using too much water, and without worrying that they might wilt.
But it also helps improve quality. “Monitoring raises your awareness of what’s happening in the vineyards,” says Holler. “Most of the problems I’ve seen in vineyards comes from negligence.”
He first started monitoring the vineyard with a wireless weather station. “It was some help, but not enough, he says. “The vineyard has four blocks and I only had one weather station. I needed more data.”
Holler built the first generation of the system with some raw technology from Crossbow. The current nodes—the yellow containers—are called eKo, and are the invention of Crossbow’s chief technology officer, Alan Broad. They are also used in other sensor networks applications, like environmental research. And of course, a very logical step would be to use them for control as well as monitoring—jobs like opening irrigation valves or starting and stopping pumps.
[Editor's Note: A longer version of this article originally appeared in Mellgren's publication Ny Teknik. This abridged translation is published by permission.]