A New Leaf for Precision Farming

Researchers at the University of California, Davis, have developed sensor-based technology that helps farmers optimize crop irrigation. A wireless communications company is now licensing the technology as an IoT solution.
By Mary Catherine O'Connor
Oct 09, 2015

How much water do crops need, and when do they need it, in order to optimize a grower's yield and/or the quality of the produce? Those are questions that Shrinivasa Upadhyaya, a professor of biological and agricultural engineering at the University of California, Davis, was asking well before the four-year-old severe drought hit California's central valley. Now, with water resources in that area stretched extremely thin, those questions are even more urgent.

LeafMon, the third generation of sensor-based technology developed in Upadhyaya's lab, can provide the answers, he says. Winemaker E&J Gallo is using LeafMon units at one of its Northern California vineyards. The technology calculates how hard an individual plant is working to transpire, and then uses that data as an indication of whether it (and, by extension, the entire crop) is under stress—and, therefore, needs more water.

The LeafMon device
Upadhyaya and his team, having secured grant funding from the U.S. Department of Agriculture's National Institute of Food and Agriculture, began investigating ways in which growers could utilize technology to reduce their water output around 2010. The team's approach was to make a system that could replace a pressure chamber, which is the conventional means of measuring a plant's water stress. With a pressure chamber, a grower places a leaf stem into an air-tight chamber and measures the amount of pressure required to pull water from the inside of the stem to the cut surface.

Plants pull moisture from the root system to the leaves, where the moisture is pulled out into the air via transpiration. As soil dries, the leaves are still transpiring, so the vascular tissue in the roots that moves water up to the leaves comes under greater physical pressure. The higher the amount of pressure (measured in bars) required to pull moisture out of a stem in a pressure chamber, the greater water stress the plant is experiencing.

The problem with using pressure chambers, Upadhyaya says, is that they require growers to go out into the field and conduct the painstaking test manually. This, he notes, is very time- and labor-intensive.

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