Stanford team finds use of satellites can estimate crop yields

Scientists at Stanford’s School on Earth, Energy and Environmental Sciences have found a way to use satellites to predict crop yields.

The research team, led by Kaiyu Guan, is using satellites that measure solar-induced fluorescence, which is emitted by growing plants. Satellites have been used by NASA since 1972 to use "greenness," which is the color of reflected sunlight, to map plant cover over the globe.

"This was an amazing breakthrough that fundamentally changed the way we view or planet," Joe Berry, professor of global ecology at the Carnegie Institution for Science and a co-author of the study, said. "However, these vegetation maps are not ideal predictors of crop productivity. What we need to know is growth rate rather than greenness."

The study, published in the journal Global Change Biology, showed that researchers can tell what size plant yield is expected but cannot measure flux. "What we need to measure is flux – the carbon dioxide that is exchanged between plants and the atmosphere – to understand photosynthesis and plant growth," Guan said. "How do you use color to infer flux? That's a big gap."

The research team plans to continue its research in the United States while trying to expand to other parts of the world.

"In the future, we hope to directly use this technology to monitor global food production, for example in China or Brazil, or even in your backyard," Guan said.