Measuring crop yields from space: New scientific discovery focused on crop growth

A new scientific discovery will help everyone involved in ensuring food supply can meet growing global demand – from the individual farmer to government agencies. A Stanford research team led by Dr. Kaiyu Guan, a postdoctoral fellow in Earth System Science at Stanford’s School of Earth, Energy, & Environmental Sciences, and Joe Berry, senior scientist with global ecology at the Carnegie Institution for Science, recently discovered a new way to measure crop yields from space. While scientists have been using satellites to capture and record agricultural data since around 1972, today’s tools make even the most progressive science fiction seem out of date.

Last fall, researchers at Stanford University developed a new method to measure crop yields using satellites to measure a special light emitted by plants during growth stages. “We have a major breakthrough from measuring the crop color, to measuring the exact crop productivity,” says Dr. Guan. “What we found is a new technology called fluorescence, and we can use this information to directly infer the photosynthesis, which we know is the primary component of the productive crop.”

From this research, the Stanford research team learned that plants in fact glow while they’re doing photosynthesis, which is quite specific to the process of photosynthesis. Since discovering this, the team has been pushing the envelope to see just what can they do with this glow now that they can measure it. One of the areas that has been very useful in this respect is the ability to look at the yield of large agricultural areas, particularly the Midwestern U.S., in relation to how much of this chlorophyll fluorescence is being emitted by the crops.

“What we’ve been able to do in the last couple of years is tap into another way of looking at crops,” says Berry. “This comes about because when plants absorb light, and are in a position to use that energy for doing photosynthesis, some small fraction of that leaks back out as an emitted light.”

So far they’ve been able to quantify this research in the Midwestern U.S. because the USDA keeps county by county yield records showing how much is planted, what is planted and what the yields are. This information can be used together with the fluorescence measurements to essentially come up with a calibration curve that could be applied anywhere in the world. By applying this technology in other parts of the world, the rationale is to build a global food production focused system using these new satellite data sets.

“The global population is expected to reach nine billion by 2050, with only so much aerial landmass available,” says Dr. Guan. “This new discovery may help governments, and even individual farmers meet the demand for food and a growing population in the future.”

For more information, read the full study and results in the journal Global Change Biology.

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