Monash trials drone-based soil moisture mapping

Engineers at Melbourne’s Monash University are working with Australian farmers to help them improve irrigation practices, reduce water use and maximise crop harvest by using autonomous drone technology.

As severe drought continues to devastate farmland and impact food supply across Australia, a Monash University research team, led by Professor Jeff Walker, has spent the past two years developing a drone-based autonomous soil moisture mapping system for irrigated paddocks.

The team has recently completed field experiments using optical mapping which can determine soil moisture levels in the near-surface. The data taken from the drone can be downloaded and used to produce a map of ground soil moisture levels to inform the farmer on how best to irrigate the paddock.

While equipped with optical mapping as a proof-of-concept, the drone has now advanced to passive microwave sensing technology using L-Band waves, with further research being conducted on the potential for using P-band waves. P-Band waves are expected to be able to measure up to 15cm into the soil unimpeded by vegetation and tillage features.

Drones have the capacity to analyse soil moisture at metre-level scales within a paddock, allowing farmers to focus on specific crop irrigation. The method also overcomes the challenges of aircraft or satellite mapping which are usually weather dependent.

The team of researchers have conducted tests across two farms in regional Victoria and Tasmania. One was at a dairy farm using a centre pivot irrigator and the other was a crop farm using a linear shift irrigator.

“We need to produce 60 per cent more food with the same amount of land and water, and we can only achieve this by being more efficient with the water we use through irrigation,” Walker said.

“We need to know how much the crop needs, how much moisture is already there and apply just the right amounts of water in the correct places to avoid wastage while keeping the crop at its peak growth.

“If the soil is too dry, crops can fail due to a lack of water. But if the soil is too wet, crops can not only fail but pests and diseases can flourish.”

Walker said while the farming industry has welcomed smarter and more automated practices, there are few tools available to farmers.

“At best, farmers might have a single soil moisture sensor in a paddock, but this doesn’t allow for the optimal application of water, especially as this resource becomes scarcer,” Walker explained.

“Plus it won’t take into account moisture variation levels across the individual paddocks.”

Therefore, Australian farmers need to become more efficient in soil moisture mapping by using ‘precision agriculture’ methods such as autonomous soil moisture mapping using drones, Walker said.

“Farmers also need to cooperate; water conservation and efficiency is a collective responsibility. Everyone needs to do their part to use water more effectively or we’re at risk of running out completely,” he said.

“As the world’s driest continent facing climate change, a growing population and a greater demand for food, water conservation should be one of Australia’s top priorities.”

The Autonomous Drones for Soil Moisture Mapping project was funded by Monash Infrastructure through a seed funding scheme and forms part of Walker’s wider research into soil moisture mapping and autonomous farming.