From backyard garden to global agriculture
Agricultural scientist Dr Xia (Emma) Liang has travelled to Laos to work with local farmers and researchers on reducing nitrogen pollution from crops
Published 15 August 2025
Growing up in Shanxi, China, I was always fascinated by my Dad’s vegetable garden. He had a knack for growing things, and I loved watching the different crops change from day to day in our backyard.
That early fascination ultimately led me to pursue a career in agricultural science.
Today, my research focuses on nitrogen use in agriculture. Nitrogen is vital for feeding a growing population and is the most used fertiliser nutrient in the world. But its excessive use can damage ecosystems, contribute to greenhouse gas emissions and degrade soil and water quality.
Unlike carbon, where the goal is simple – to reduce emissions – addressing nitrogen pollution is more complex because it interacts with soil, climate and ecosystems in different ways.
Nitrogen contributes to acidification and eutrophication (excess nutrients) in waterways, leading to smog and acid rain, as well as intensifying the greenhouse effect and ozone depletion.
Excess nitrogen also leads to soil acidification, forest dieback, and biodiversity loss in terrestrial ecosystems. With a predicted 9 billion people to feed by 2037, striking the right balance is the real challenge.
I’ve had the opportunity to work on research projects around the world. Right now, I’m in Laos, leading an aid project funded by the Australian Centre for International Agricultural Research (ACIAR) to help farmers integrate more sustainable practices and increase rice production.
Laos has a rich history of rice farming, but many Lao farmers are facing mounting challenges: poor soil fertility, limited access to resources, and rising costs. Climate change is making these issues worse, with increasingly frequent droughts and floods.
We’re working directly with farmers and local partners to improve productivity and sustainability. In this first year of the five-year project, we’re focused on soil profiling, farm demonstrations and community engagement – talking with farmers and stakeholders to understand their needs and share knowledge.
The project is based on collaboration and building long-term relationships in Laos.
Despite the hardships, Lao farmers are some of the kindest and happiest people I’ve met. It’s inspiring to learn about their culture and traditional farming practices.
One of my favourite experiences has been sharing sticky rice with locals, served warm in small bamboo baskets called Lao aep khao, rolled into balls by hand and eaten with a variety of dipping sauces.
The farmers are always generous with their knowledge, which makes collaboration meaningful.
Next year, our work will expand to include more advanced field experiments. We’ll be measuring and modelling emissions – like nitrous oxide (N₂O), methane (CH₄) and ammonia (NH₃) – and tracking nutrient runoff and leaching from different fertiliser applications.
Methane is released from rice paddies when organic matter breaks down in flooded, oxygen-poor conditions.
Sciences & Technology
Nitrogen pollution: Forgotten element of climate change
Nitrous oxide is emitted when fields shift between wet and dry, particularly after nitrogen fertiliser use, while ammonia is lost mainly from surface-applied urea – a common nitrogen fertiliser – in hot, high-pH environments.
These gases contribute to global warming, air pollution and ozone depletion. Using techniques like open-path FTIR spectroscopy, which directly measure gases from their sources, and specialised growth chambers, we will quantify nitrogen emissions over time.
Our goal is to develop evidence-based nutrient management practices that improve productivity while minimising environmental harm. We’re also laying the groundwork for certifying Lao rice with sustainability credentials, especially for export markets.
We’re collaborating with three local partners: the Lao National Agriculture Forestry Research Institute (NAFRI), the Department of Agricultural Land Management (DALaM) and the Faculty of Agriculture at the National University of Laos.
A key focus of our project is capacity building, including strengthening soil testing labs, refining experimental protocols and providing long-term support so that the research benefits local communities beyond the life of the project.
We also hope our findings can be applied in neighbouring countries like Cambodia.
I was introduced to the concept of a ‘nitrogen footprint’ during my PhD. My supervisor, Professor Deli Chen, encouraged me to calculate Australia’s nitrogen footprint for the first time.
Despite its ‘clean and green’ image, Australia has the largest nitrogen footprint (up to 47 kilograms of nitrogen per person each year) of any country using the N-Calculator model. Australia’s footprint is mostly due to beef consumption and coal-based electricity.
We then assessed the University of Melbourne’s institutional nitrogen footprint – the first study of its kind in Australia to show how universities can use these models to monitor and improve the sustainability of their operations and governance.
Sciences & Technology
What you need to know about nitrogen pollution
People often don’t realise how everyday choices – what we eat, how we travel, how we use energy – can contribute to nitrogen pollution.
That’s why tools like nitrogen footprint calculators and nitrogen life cycle assessments are so valuable: they help make this information accessible to the public.
What I love most about my research is the opportunity to collaborate with many different groups – from farmers and government to researchers, industry and consumers. Research is only one piece of the puzzle.
I’m part of the ARC Research Hub for Smart Fertilisers – led by Professor Chen. It’s a multidisciplinary program bringing together experts in soil science, chemistry, plant science, engineering and industry.
It’s this kind of collaboration that’s key to solving global challenges in agriculture.
My journey hasn’t been without its challenges. When I moved to Australia as a PhD student, English wasn’t my first language, and cultural differences made communication difficult.
Mentorship played a huge role in building my confidence as a researcher.
Professor Deli Chen encouraged me to step outside my comfort zone, and my co-supervisor, Associate Professor Shu Kee (Raymond) Lam, supported me through the many ups and downs of research.
Their guidance has been invaluable, and I encourage early-career academics to build connections with mentors they admire.
It feels good to work on projects that contribute to global food security and environmental sustainability.
My passion for agriculture has taken me from my Dad’s vegetable garden in China to the rice fields of Laos – and I’m excited for what’s to come.
– As told to Cassidy Mogg and Lewis Barnaby
This story was written by Master’s students as part of the Science Communication subject.
