Not one to shy away from a challenge, Soil CRC PhD student Rohan Samaratunga is fascinated by the complexity of improving soil health and is driven by a desire to conserve nature and strengthen ecosystems.
“Soil is a highly dynamic system composed of living organisms, weathered minerals, water and air, all interacting to support plant growth,” Rohan said. “To understand soil health, you first need to understand the roles and interactions of both macro- and micro-organisms.”
This understanding is critical for his PhD research, which is focussed on developing a climate-smart algae-based biofertiliser that can persist in the soil, enhance soil health and improve crop productivity and resilience under Australia’s harsh farming conditions.
“In the early stages of my project, I successfully developed algae-based consortia in the laboratory and introduced them into soil systems in greenhouse experiments. I am currently monitoring their establishment and assessing their impact on soil biological and physicochemical properties.”
By the end of his PhD, Rohan aims to identify top-performing algal consortia as biofertilisers by evaluating them in greenhouse and field trials with major field crops.
“In parallel, I am working to improve algal biomass productivity using bioreactors and to develop low-cost growth media to support scalability and future commercialisation.”
The successful development of algae-based biofertilisers could directly benefit Australian farmers by improving soil health, crop performance and farm sustainability. Because, as Rohan notes, “Healthier soils support more resilient farming systems and reduce reliance on synthetic inputs.”
Beyond the farm gate, this research contributes to broader ecosystem sustainability, as algae act as primary producers within soil systems and fix carbon.
“The outcomes may also support the fertiliser industry by providing sustainable alternatives and creating new pathways for researchers and industry partners to diversify and improve biofertiliser products,” Rohan said.
Where it began
Growing up in Sri Lanka, Rohan Samaratunga was exposed to agriculture from a young age. Tea plantations, vegetable farming and paddy (rice) cultivation were part of community life and sparked a long-term interest in preserving soils and nature.
“These early experiences laid the foundation for my passion for agriculture and ultimately guided me towards research,” Rohan said.
“I pursued and completed my Bachelor of Science in Agriculture in Sri Lanka and built my early career primarily in horticulture, before moving to Australia with my family in 2014.”
Here, despite the obvious cultural differences, Rohan says he could see similarities in the importance that Australians and Sri Lankans place in the care and conservation of nature and the significant impact of agriculture on local communities.
“Farming in Australia plays a vital role in the national economy; however, it faces challenges due to a changing climate. As someone passionate about conserving nature, I considered using science and microbes, such as algae, which are underexplored in the soil arena, to help address this challenge,” Rohan enthused.
This motivated him to pursue further research that could have a meaningful impact and he applied for a PhD with the University of Newcastle and the Soil CRC in 2024.
“I believe my research has the potential to support Australian agriculture, strengthen ecosystems, and contribute to the development of sustainable biofertiliser technologies.”
How it’s going
Rohan said he is proud of progressing through his research plan step-by-step and seeing his project develop in a structured and meaningful way.
“Alongside this progress, I have significantly strengthened my laboratory, experimental and analytical skills, including working with state-of-the-art equipment at the University of Newcastle,” he said.
“My PhD journey has also enhanced my communication, presentation, technical writing and problem-solving abilities, which I see as valuable strengths for my future career.”
When asked what he is enjoying most about his PhD, Rohan said he likes the collaborative nature of his project and working with a wide range of people across research, industry and farming communities.
“I particularly value working with my experienced supervisors – Prof Megh Mallavarapu and Dr Abinandan Sudharsanam from the University of Newcastle and Prof Chengrong Chen from Griffith University. They are open-minded and supportive, encourage independent thinking, and have helped me to refine my research ideas and skills,” he said.
“I also enjoy participating in Soil CRC events and training, which provide valuable opportunities to engage with leading researchers, industry professionals, farmer groups and fellow PhD students.
“Field visits and soil sampling have been especially rewarding, as they expose me to real Australian farming conditions and help ensure my research remains focused on practical, end-user outcomes.”
What comes next
With a little over a year and a half to go before he completes his PhD, Rohan says he is open-minded about his future career and is considering pathways across academia, industry and applied research.
“My long-term goal is to build a career that aligns with my skills and values, supports sustainable agriculture, and meets both organisational objectives and broader societal needs,” he said.
Outside of his research work, you will find Rohan in his garden, growing vegetables, fruits and ornamental flowering plants.
“I also maintain an aquarium, which allows me to explore aquatic ecosystems and learn about fish behaviour and system balance,” he said.
Whether at work or at play, Rohan is eager to take on new challenges, continue learning, and make a valuable contribution to a more resilient environment and a sustainable future.
“I am always motivated to identify opportunities for improvement and to approach challenges in my own way, aiming to create solutions that make a meaningful, lasting impact.”