Unlocking the secrets of carbon in soil to protect local food supplies

Agriculture accounts for one-third of CO2 emissions in Australia, making it one of Australia’s largest contributors to greenhouse gas emissions in our environment. Agricultural scientists sit at the frontline of science to secure our soil and food supply against the rising threats of global warming.

Allie Zheng and Rachel Davis are two PhD students working at La Trobe’s world-renowned AgriBio facility. Their goal is to uncover the impact elevated carbon dioxide emissions and the use of nitrogen fertilisers in farming will have on the carbon balance in Australian soil – a vital component in crop production and plant growth in our local ecosystems.

Mitigating climate change through microbial research

Rachel’s research looks at the impact of elevated atmosphere CO2 on plants by exposing plants to high CO2 levels. This is to assess how microbes present in soil respond to elevated CO2 levels under plantation, and what effect this has on soil carbon and eventually our crops.

Her research works toward understanding how elevated CO2 levels will impact existing carbon in soil, providing data that’ll help us understand the impact of climate change.

‘No one is investigating the microbes just yet. There’s this massive gap in the literature on how the microbes contribute to the release of carbon in the soil.’

The emissions of carbon from the soil is going to be a massive issue in the future,’ Rachel explains. ‘The science behind this is so complex. We’re at the forefront of that research to figure out what elevated CO2 levels will do to Australian soils.’

Microbes are microscopic organisms that found everywhere in our world – in our water, soil and the air we breathe.

Rachel’s project will specifically look at soil microbes – a critical component for maintaining soil and plant health. Soil microbes break down organic matter, which is key to holding nutrients in the soil. This is a vital process for helping plants thrive and protecting the functioning of our ecosystems.

‘We know that CO2 levels are increasing, and unfortunately we can’t stop all production of CO2 into our atmosphere. We need to explore how microbes are possibly changing the functions they are performing, which will help to measure the impact they will have on our farming communities.

If we figure out what they’re doing exactly, we might be able to help keep the carbon in the soil instead of it being released into the environment’.

Protecting our nation’s food supply through soil research

Allie’s research specifically looks at the priming effect in soil – an important process which affects balance carbon within soil. The priming effect is a process where new carbon stimulates or suppresses the loss of existing carbon in soil.

Her research into the priming effect is a field that has intensified in the last decade, due to the increased awareness about the importance of soil carbon for climate change and food security.

‘Soil carbon is what I’m very interested in’ Allie says. ‘Specifically, the priming effect – why the priming effect happens in the soil, what factors regulate it, and if we can supress this process to sequester more carbon into the soil.

The ultimate goal is to keep more carbon into the soil and this would have a direct impact on improving food production and help mitigate some of the effects of climate change’.

Soil is one of the major carbon stores on our planet, holding up to three times more carbon than what’s present in our atmosphere. Most carbon is stored within organic matter in our soil, however unsustainable agricultural and farming practices stimulates carbon loss from soil into our atmosphere – a big contributor to increasing CO2emissions.

Allie’s research looks into the application of nitrogen fertiliser and the impact on the priming effect. Modern agricultural practices rely heavily on the use of nitrogen fertiliser to maximise crop yield, however it comes at an environmental cost.

‘The application of nitrogen fertilisers is increasing all over the world in order to increase food production. In my research I am looking at nitrogen fertilisers and the priming effect on different types of soil and land uses. I am looking at what the role of nitrogen fertilisers in the priming effect, and what are the mechanisms because currently the conclusions from research are still not clear’.

Grounded in the present, reaching into the future

Allie and Rachel’s research have far-reaching implications in understanding how nitrogen fertilisers and increased CO2 in our atmosphere will impact crop production in the future. This can help us develop real-world solutions to mitigate the impact of climate change on crop yield.

‘The reason why I chose to pursue agricultural science is because of the importance of soils on climate change and food production.’ Allie explains. ‘Climate change and the environment is a big topic and is a great challenge to society – so we’re going to need to prepare for that.’

When designing sustainable solutions for the future, there’s no one-size-fits-all approach. ‘Australian soil is very different to other soil types around the world’, Rachel explains. ‘Australian soils are so understudied and very susceptible to change, so there’s all this research that has been done in countries like China or America but they can’t be applied to Australia soils – so it’s very important for us to figure out what is going on and what’s going to happen here.’

‘With a growing population, we’re going to need to figure out how we can feed everyone,’ Rachel says. ‘Every farmer relies on fertiliser for a higher crop yield, but it’s not going to be very sustainable without scientific practice. So, the challenge will be about trying to find that balance between sustainability and increasing crop yield.’


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About our researchers

Allie Zheng is a PhD candidate in the Soil-Plant Interaction group in AgriBio. Her research is about how nitrogen fertilisation affects the decomposition of native soil organic carbon following the fresh carbon input (priming effect).

Rachel Davis is a PhD candidate crossed between the Soil-Plant Interaction group in Agribio, as well as the Applied and Environmental Microbiology lab. Her research looks at the below-ground responses to above-ground high CO2 levels, and the role of rhizosphere priming in soil carbon cycle. You can follow her on Twitter.

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