Subsoil sensor

A sensor that monitors how effectively a plant takes up water and nutrients from the soil could help farmers grow drought-resistant crops within the next decade.

The device is being developed by researchers at Manchester University to identify plant varieties that are tolerant to future climate conditions. Based on electrical imaging techniques used in healthcare and manufacturing, the team have adapted the technology for use in the subsoil analysis of plant behaviour.

Principal investigator Dr Bruce Grieve, from the Syngenta Sensors University Innovation Centre, said: ‘If you can monitor a chemical plant for how well a pressure filter is operating, then you can apply the same technique to soil, which is effectively also a filter for water and nutrients. We’re hoping to create an image reconstruction of the water movement using a soft-field sensor to examine how different plants draw on their surrounding moisture.’

The sensor is made up of metal plates sunk into the soil. An electrical current is sent through these plates producing bending electrical-field lines that respond to particles in the water. These electrical fields are then picked up by a series of volt meters and converted into a basic image using software that details the size and shape of the root structure, and tracks how efficiently it takes in water.

Grieve said: ‘Farmers could use [the sensors] for detecting genetics. If you’re trying to breed a drought-tolerant crop then you want to see how efficiently different varieties of crop can draw on that moisture. By using electrical imaging techniques you accelerate time to market and the time a farmer can start growing these crops.’ Currently, crops are selected based on features that indicate stronger genetics, such as an additional ear of corn on a maize plant. Undesirable crops are weeded out, leaving the healthier crops to survive and produce a new line of plant.

However, the process is labour intensive and with food security a global concern, Grieve said the development of a sensor that improves the understanding of crop environments will be a valuable addition to the agricultural industry.

‘We’re bringing a non-biological viewpoint on how you would change the farmer of the future. With subsoil-monitoring techniques you will get a real-time indication of which are the most efficient crops,’ he said. ‘[In] the longer term, it’s not a massive leap of faith to monitor a wider area and map the irrigation movements using a wireless sensor system within a field.’

Over the next six months, the team plans to test its sensor in a greenhouse environment using a single genetic strain of plant. If successful, the results will be integrated into parallel research projects, including work carried out by Nottingham University on X-ray tomography. Grieve hopes to develop a low-cost system that is suitable for the field environment within the next decade.

Ellie Zolfagharifard