Developed by engineers at the University of Connecticut, the small sensors take readings from different depths of soil and feed the data back to an instrument on the surface via a wired connection. According to the UConn team, the $2 sensors are easy to insert into the earth, as well as significantly less expensive than alternatives that are currently available.
The technology, described in the Journal of Sensors and Actuators, was tested on the university’s farm over a ten-month period. According to the team, it performed well compared with commercial sensors that ranged from $100-$1000, which were tested alongside the prototypes. What’s more, the sensors are small enough to be distributed easily around the world and could help address global problems related to irrigation and crop health.
“Advances in hydrological science are hampered by the lack of on-site soil moisture data," said Guiling Wang, study author and professor of civil and environmental engineering at UConn.
"It's really hard to monitor and measure things underground. The challenge is that the existing sensors are very expensive and the installation process is very labour-intensive."
Accurate soil monitoring is essential to ensure a water level that produces robust crops while minimising water use. In the US states of Florida and California, irrigation water usage is already tightly restricted, with droughts and climate change pushing resources to the limit.
Remote sensing technology such as satellite radar can be used to track soil moisture, but the low resolution makes modelling difficult. Conversely, the new sensor system delivers the high spatio-temporal resolution data needed for hydrology model development. In addition to hydrology modelling, the team has plans for a nitrogen sensor based on the same technology, which could help provide an even richer picture of soil health.
"This is really an exciting start to a much larger scope of things we have in mind," said UConn’s Baikun LiLi, study author and professor of civil and environmental engineering.