Data from satellite sensors show that during the Northern Hemisphere’s growing season, the Midwest region of the United States boasts more photosynthetic activity than any other spot on Earth, according to NASA and university scientists.
Recent research from the NASA Goddard Space Flight Center in Greenbelt, Md., demonstrated that fluorescence from plants could be teased out of data from existing satellites, and a new study used the data for the first time to estimate photosynthesis from agriculture. Results were published March 25 in Proceedings of the National Academy of Sciences.
According to co-author Christian Frankenberg of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., “The paper shows that fluorescence is a much better proxy for agricultural productivity than anything we’ve had before. This can go a long way regarding monitoring – and maybe even predicting – regional crop yields.”
Most of the year the study found that the tropics are most productive. But during the Northern Hemisphere’s growing season, the U.S. Corn Belt “really stands out,” Frankenberg said. “Areas all over the world are not as productive as this area.”
Data showed that fluorescence from the Corn Belt, which extends from Ohio to Nebraska and Kansas, peaks in July at levels 40 percent greater than those observed in the Amazon.
The analysis revealed that carbon cycle models – which scientists use to understand how carbon cycles through the ocean, land and atmosphere over time – underestimate the productivity of the Corn Belt by 40 to 60 percent.
Unlike most vegetation, food crops are managed to maximize productivity. They usually have access to abundant nutrients and are irrigated. The Corn Belt, for example, receives water from the Mississippi River. Accounting for irrigation is currently a challenge for models, which is one reason why they underestimate agricultural productivity.
According to Frankenberg, the remote sensing-based techniques now available could be a powerful monitoring tool for food security, especially data from OCO-2 and in combination with data from other upcoming satellites, such as NASA’s Soil Moisture Active Passive, scheduled for launch later this year.