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
