Drones are creating a new agricultural revolution. It is estimated that the scale of UAVs in the agricultural market will reach billions of dollars in the next few years. Gerard Sylvester, an information expert and editor of the food and Agriculture Organization of the United Nations (FAO) and the International Telecommunication Union (ITU) Research Report on “unmanned aerial vehicles and agriculture”, said that as farmers try to adapt to climate change and other challenges, unmanned aerial vehicles are expected to help improve the efficiency of agricultural enterprises as a whole.
When the UAV is equipped with cameras and other data acquisition equipment, it becomes the “eye of the sky”. In some countries, drones have been used regularly to transport fertilizers or pesticides. U.S. farmers, including grape growers in California and New York, have been experimenting with drones to investigate “low activity” areas that lack water or cannot be absorbed by the soil.
Although UAVs are becoming extremely powerful, they are still not “perfect”: for example, how to distinguish weeds from crops requires special perception. Nevertheless, UAVs may soon become standard accessories for agricultural machinery. Here are some examples of potential applications of UAVs in agriculture
1. Crop assessment
It takes a lot of time and manpower to monitor the entire crop growing area, and UAVs can quickly scan and inspect to find plants that grow slowly and may need remedial measures.
The sensor can monitor the absorption and reflection of specific wavelengths of light, form a color contrast image, and intuitively reflect the problem area. The images generated from these data include NDVI (normalized difference vegetation index) map, which is obtained by calculating the difference ratio of near-infrared and visible radiation, and obtained by satellite images and long-term monitoring of UAV.
In this way, soil, crops and forests can be distinguished, and sick plants can be found, because plants that are harmed or dehydrated reflect light in different ways. Recent studies have shown that this spectral data can be used to detect crops damaged by floating pesticides, as well as weeds that grow in crops and are immune to herbicides.
As shown above, the researchers conducted experiments on a wheat field in Ontario, Canada, using UAVs equipped with sensors to survey the field. The resulting map highlights areas that need further investigation: on the NDVI map, there is a worm infested area (area B), next to healthy crops without infection (area a). You can also see the rock (area D), and the area where the wheat stalk was damaged is highlighted in bright pink on the map.
2. Herd monitoring
Cattle ranchers use drones to track their livestock on vast farms and find out where fences need to be fixed. When equipped with high-definition thermal imagers and night cameras, drones can also help investigate animals that may be harassing and attacking herds. In India’s Kaziranga National Park, the drone has also become a tool for tracking human poachers.
The early efforts of NASA to monitor vegetation growth in the Great Plains by satellite promoted the development of NDVI. Plant leaves can absorb and reflect different wavelengths of light: chlorophyll in healthy leaves absorbs visible light and reflects near-infrared light. Yellow, compressed leaves and dead leaves (as well as rocks that act as soil) reflect and absorb these wavelengths in different ways. UAVs equipped with sensors can collect these spectral data and create maps showing changes in crop health.
3. Disease surveillance
Pathogens that cause plants to wilt and otherwise damage crops can escape detection without careful scrutiny.
Although spectral imaging technology can reveal etiolated plants in green plants, Virginia Tech’s Schmale is using drones to detect pathogens floating in empty spaces that have not yet landed. He has captured the airborne spores of the fungus Fusarium graminearum, which can destroy wheat and corn and has gone several kilometers or more.
If farmers are aware of a pathogen outbreak in a nearby county, air sampling can alert them to the impending outbreak. Federal and state agencies can also monitor pathogens on a larger scale, enabling farmers to prepare for an outbreak.
4. Moisture monitoring
Soil moisture absorption is often uneven. Some parts may dry faster than others, or may be missed by watering equipment.
Spectral and thermal imaging can reveal the dry point of crop wilt. Imaging can also detect leaks from equipment and irrigation channels. More importantly, farmers can use airborne laser scanning technology or software that stitches thousands of high-quality aerial photos into 3D maps to assess the terrain of their land.
These maps identify catchment areas, reveal the direction of water flow at the bottom of each tree in the orchard, and identify other land features that may affect crop health and soil erosion.
5. Mechanical pollinator
In fact, honeybee robots may not help pollination much, but drones may one day help real bees.
A New York based start-up has developed a pollen dumping drone to help pollinate fruits such as almonds, cherries and apples. The company reported that its drone pollination rate could be increased from 25% to 65%, but external analysis has yet to verify these figures. Nevertheless, some fruit growers are optimistic that UAVs may be useful in orchards.
Editor in charge: GT