Mike Grodzki of Teledyne Imaging explains the impact of how shortwave infrared imaging (SWIR) is adding precision to agriculture.
Whatever your stance on the causes of climate change, the data related to the results are stark. The United Nations estimates that the world’s farmers will have to produce 70 percent more food using just five percent more land by 2050. That’s a difficult equation to compute.
In California’s Central Valley—the seven-million-acre region where more than half of the fruits, vegetables and nuts produced in the US are grown—long-time farmers are proud of their innovation and accustomed to tough equations. After all, since the 1930s, they have managed to consistently harvest almost 10 percent of the country’s agricultural output—by value—on less than one percent of the country’s farmland. They’ve succeeded by mastering long-range irrigation and groundwater extraction. Every year, more than 250 different crops are grown in the Central Valley, with an estimated value of $17 billion.
Over an area southwest of Sacramento, the effect can be clearly seen in these two February satellite images acquired in 2014 and 2003. Vegetation is depicted in shades of red, while barren fields are dark brown and gray.
The left image was acquired on Feb. 11, 2014 by Landsat 8, and the right image was acquired 11 years earlier, on Feb. 8, 2003 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA’s Terra spacecraft. The great increase of barren fields, and the bare hills in the southwest corner, are readily apparent. The images cover an area of 7.4 by 13.5 miles (12 by 21.7 kilometers). Image courtesy of NASA.
As skilled as the agrarian visionaries of the Central Valley are, they had run out of tricks when a string of drought years in the first two decades of the century threatened to decimate America’s market garden. Between 2012 and 2016 alone, the estimated groundwater volume fell by ten cubic miles.
The fact that the western edge of the valley is just 100 miles from the heart of another valley, where silicon is valued more highly than celery, has turned out to be quite fortuitous. Contemporary infrared scanning technology is providing the farmers of the Central Valley, and others much farther afield, with a new technique for boosting the chances for good harvests, using water more efficiently, and moving toward what is being termed precision farming. It required a new type of imaging.
A trick of the light
Developed for military use, during the last decade, infrared scanning has become a widespread technology for applications such as predicting water stress in crops and fruit yield, planning irrigation scheduling, detecting disease and pathogens in plants, and evaluating fruit maturation. Farther down the food chain, thermal imaging is used to detect the ripeness of fruits and vegetables at distribution points and in retail outlets, and for detecting foreign bodies in foods.
The technology uses the fundamental science of infrared radiation, which Sir William Herschel, a German-born astronomer, discovered in 1800.
Working in England, two decades after discovering the presence of the planet Uranus, Herschel observed that sunlight produced significantly more heat when passed through a red filter. Passing the sunlight through a prism and measuring the temperatures produced by various colours, he surmised that the highest temperatures existed beyond the visible light rays, in what he termed “calorific rays.”
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