According to a NASA press release, data from satellite sensors show that during the growing season, the Midwest region of the United States shows more photosynthetic activity than any other spot on Earth.
Healthy plants convert light to energy via photosynthesis and chlorophyll emits a fraction of absorbed light that is invisible to the naked eye. That is what the satellite shows and it is an indicator of the amount of photosynthesis of plants in a given region.
On an annual basis a study showed that the tropics are the most productive, but during the growing season, the U.S. Corn Belt stands out as the most productive area across the world.
The data that NASA collected shows that fluorescence from the Corn Belt peaks in July at levels 40 percent greater than those observed in the Amazon.