Sweet smell of success for ‘eNose’ project

With participating organisations University of Tasmania, Soils for Life, Birchip Cropping GroupFarmlink Research, Southern Farming Systems 

By Dr Shane Powell, Senior Lecturer, Tasmanina Insititute of Agriculture. 

By ‘smelling soil’, researchers hope to identify soils that have specific ‘signatures’ associated with particular characteristics.  

Led by the Tasmanian Institute of Agriculture (TIA), with input from participating organisation growers, a Soils CRC project, is aiming to develop alternative ways of assessing soil health.  

Growers want to know more about how their soils are performing and how their management activities affect the way soil functions. Our aim is to use low cost commercially available sensors to build an eNose that can detect gases in soils.  

So what does the eNose actually ‘smell’?  

Microorganisms in the soil produce many chemicals including volatile organic carbons (VOCs) which are small carbon-based molecules that evaporate easily. Different types of microbes produce different VOCs which the eNose can detect and these can be used to provide an indication of how the soil microorganisms are functioning. This allows growers to monitor changes in their soil to inform decisions about land management practices. 

For example, our trials have shown our eNose can differentiate between different soil types and it can detect changes as soil dries out or becomes water-logged. We also have data from a small trial that suggests the eNose detects different signals from soil in which plants have been inoculated with nitrogen-fixing rhizobia compared to soil in which the plants have not been inoculated. In other words, the eNose can detect differences in microbial activity in the soil. 

Different growers have different questions about their soil microbes – questions that are not readily answered by traditional and time-consuming microbial tests. Clearly, an eNose will need to do more than ‘one thing’ and it will need to do it efficiently. 

Growers have indicated they would like a simple readout but also the ability to look more deeply into their soil data when they are ready. This won’t be easy because the eNose generates an enormous amount of data – but we are working on ways to analyse and interpret the eNose signals. 

One way to solve this problem is to simulate human sensory skills, whereby when we smell soil with our nose the brain tells us whether it is a ‘healthy’ smell or not. This inspired us to try using a neural network as the ‘brain’ for our electronic ‘nose’. An early prototype is over 99 per cent accurate at telling the difference between a soil that is sustaining native timber and the same soil with a vegetable crop. 

We are also starting to design how the eNose will function in the field: power supply and protection from adverse environmental conditions are two big issues to be solved. Solar power is one solution but what happens at night and how long can the battery last when it gets cold? How do we protect it from curious wildlife? 

All the while we consider the long list of features in the e-nose that growers asked for: everything from connecting to an App on their phone and archiving their data to providing advice on the most compatible crops for that soil. Some of these ideas can be incorporated into our prototypes, some are ideas for a later version and/or for the day when other technology makes it feasible. 

Our plans for testing of prototype eNoses with growers have been on hold since March although our grower group partners are keen to find ways to continue to work with us and their growers. As we start to plan for the next phase of eNose development we will be asking more questions from our collaborating growers! 

The eNose project is being delivered by the Soil CRC through its partners the University of Tasmania, Southern Farming Systems, Soils for Life, Birchip Cropping Group and FarmLink. The Soil CRC is funded by the Australian Government and participant organisations.  

TIA is a joint venture between the University of Tasmania and the Tasmanian Government. 

Find out more about project here:

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