In particular, soil monitoring conditions hold great promise for helping farmers use water more efficiently. Sensors can now be wirelessly integrated into irrigation systems to provide real-time awareness of soil moisture levels. Studies indicate that this strategy can reduce water requirements for irrigation by anywhere from 20% to 72% without hampering daily operations in crop fields.
What is the Agricultural Internet of Things?
Even in dry places like the Middle East and North Africa, farming is possible with effective water management. But extreme weather events driven by climate change make it more difficult. Repeated droughts in the western United States over the past 20 years, along with other disasters such as wildfires, have caused billions of dollars in crop losses.
Water experts have been measuring soil moisture to inform water management and irrigation decisions for decades. Automated technologies have largely replaced handheld soil moisture tools because it is difficult to take manual soil moisture readings in production fields in remote locations.
Over the past decade, wireless data harvesting technologies have begun to provide real-time access to soil moisture data, enabling better water management decisions. These technologies may also have many advanced IoT applications in public safety, urban infrastructure monitoring and food safety.
The Agricultural Internet of Things is a network of radios, antennas and sensors that gathers real-time information about crops and soil in the field. To facilitate data collection, these sensors and antennas are connected wirelessly with farm equipment. Ag-IoT is a complete framework that can detect conditions on farmland, suggest actions in response and send commands to agricultural machines.
Connected devices such as soil moisture and temperature sensors in the field make it possible to control irrigation systems and save water autonomously. The system can schedule irrigation, monitor environmental conditions and control farm machinery, such as planters and fertilizer applicators. Other applications include estimating nutrient levels in soil and identifying pests.
The challenges of laying networks underground
Wireless data collection has the potential to help farmers use water much more efficiently, but putting these components in the ground creates challenges. For example, at the Purdue ENT Lab, we have found that when the antennas that transmit sensor data are buried in soil, their operating characteristics change drastically depending on how moist the soil is. My new book, “Signals in the Soil,” explains how this happens.
Farmers use heavy equipment in the fields, so antennas must be dug deep enough to avoid damage. When soil becomes wet, the moisture affects the communication between the sensor network and the control system. Water in the soil absorbs signal energy, which weakens the signals that the system transmits. Dense soil also blocks signal transmission.
We have developed a theoretical model and an antenna that reduces the earth’s influence on underground communications by changing the operating frequency and system bandwidth. With this antenna, sensors placed in the uppermost soil layers can provide real-time information on the soil condition of irrigation systems at distances of up to 200 meters – longer than two football pitches.
Another solution I have developed to improve wireless communication on earth is to use directional antennas to focus signal energy in the desired direction. Antennas that direct energy into the air can also be used for long-distance wireless underground communications.
What’s next for Ag-IoT
Cybersecurity is becoming increasingly important to Ag-IoT as it matures. Networks on farms need advanced security systems to protect the information they transmit. There is also a need for solutions that enable researchers and agricultural extension agents to merge information from multiple farms. Aggregating data in this way will provide more accurate decisions on issues such as water use, while preserving producers’ privacy.
These networks must also adapt to changing local conditions, such as temperature, precipitation and wind. Seasonal changes and crop growth cycles can temporarily alter the operating conditions of Ag-IoT equipment. Using cloud computing and machine learning, researchers can help Ag-IoT respond to changes in the environment around it.
Finally, lack of high-speed Internet access remains a problem in many rural communities. For example, many researchers have integrated wireless underground sensors with Ag-IoT into center-pivot irrigation systems, but farmers without high-speed Internet access cannot install this type of technology.
Integrating satellite-based network connectivity with Ag-IoT can help unconnected farms where broadband connectivity is still unavailable. Researchers are also developing vehicle-mounted and mobile Ag-IoT platforms using drones. Systems like these can provide continuous connectivity in the field, making digital technologies available to more farmers in more locations.
Abdul Salam is an assistant professor of computer and information technology at Purdue University.
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