Eyes in the sky: Five ways drones will change agriculture
Five ways drones will change agriculture
1. Crop assessment
Monitoring fields takes time and manpower. Drones can sweep through and take stock, inspecting for slow-growing plants that might need a hit of nitrogen or some other remedy. Sensors that measure particular wavelengths of light absorbed and reflected by plants can generate color contrast images that highlight problem areas in a field. Images generated from these data include NDVI (normalized difference vegetation index) maps, which have long been created using satellites and airplanes by calculating the ratio of the difference of near-infrared and visible light radiation. Newer sensors take advantage of additional wavelengths in the light spectrum and may add filters and other resolution-enhancing tricks. Not only can soil, crop and forest be told apart, but sick plants can also be spotted because stressed or dehydrated plants reflect light differently. Recent research shows that this spectral data can reveal crops that have been injured by the drifting pesticide dicamba, and can spot herbicide-resistant weeds growing between rows.
Differentiating a weed from a crop plant within a row is still a challenge. “Green is green,” says agricultural engineer Yanbo Huang of the US Department of Agriculture’s Crop Production Systems Research Unit, in Stoneville, Mississippi. He’s working on algorithms to determine such things as leaf shape and texture that, combined with imaging information, could tell cotton from crabgrass.
2. Counting cattle
Cattle ranchers with lots of land to cover are using drones to keep track of their livestock and survey where fences need fixing. When outfitted with high-definition thermal imagers and night-capable cameras, drones can also help survey for unwanted animals that might be ravaging a herd. (Such drones have also become a tool for tracking human poachers in places like India’s Kaziranga National Park, home of the one-horned rhino.)
3. Monitoring for disease
Without close scrutiny, pathogens that wilt, wither and otherwise damage crops can escape detection and spread. While spectral imaging technologies can reveal yellowed plants within fields of green, Virginia Tech’s Schmale is using drones to ferret out high-flying pathogens before they even land. He has captured airborne spores of the fungus Fusarium graminearum, which can devastate wheat and corn, that have traveled kilometers and more. If a farmer knows of a pathogen outbreak in a nearby county, air sampling could provide an alert to its impending arrival. Federal and state agencies could also monitor for pathogens at a larger scale, allowing farmers to be at the ready before outbreaks occur.
4. Water watch
Many fields aren’t uniformly flat. Some sections may dry out faster than others or be missed by watering equipment. Spectral and thermal imaging can reveal dry spots where crops will wither. Imaging can also detect leaks in equipment and irrigation canals. What’s more, farmers can assess the topography of their land with airborne laser scanning technologies or software that stitches together thousands of high-quality aerial photos into 3D maps. These maps can identify water catchments, reveal the water-flow direction at the base of each tree in an orchard and identify other land features that influence both the health of the crop and where soil erosion might become an issue.
5. Mechanical pollinators
Actual bee drones don’t help with pollination, but the flying-robot sort may one day lend an assist to real bees. A New York–based start-up has developed pollen-dumping drones that have helped pollinate almond, cherry and apple orchards. The company reports that its drones can up pollination rates by 25 percent to 65 percent, though outside analyses verifying those numbers are yet to be done. But some fruit growers are optimistic that the drones could prove useful in orchards, especially if a cold snap keeps live bees hive-bound during the trees’ flowering window.