Research Questions/Objectives:
This project aims to investigate how cultivation and insecticide use affect soil macroinvertebrate abundance and diversity, and how these factors correlate with soil carbon in sugarcane farming systems. This will be addressed by the following questions:
Answering these questions aims to provide insights into factors limiting carbon sequestration in a major agricultural industry, which has relevance to possible climate mitigation strategies as well as more sustainable and productive farming practices that maximise biological activity and soil health.
Brief Description of the Project:
Leaving harvested sugarcane waste/trash on the surface as mulch also known as green cane trash blanketing (GCTB) has become common practice in Australian sugar cane systems for the last three decades (Salter, 2024). Despite this, there has not been the expected increase in soil carbon. This issue was recently highlighted in Sugar Research Australia’s and the Queensland Government’s (2022) “Long-term Trash Blanketing and Tillage Trial,” which emphasises the “need to understand the processes limiting improvement in soil carbon and refine trash management to capture greater benefits from this resource.”
My project investigates one potential limiting factor: the impact of farming practices on soil macroinvertebrates and their essential ecosystem services. Practices such as cultivation and insecticide use are well-documented stressors that reduce macroinvertebrate abundance and diversity by disrupting soil ecosystems and eliminating beneficial fauna (Sheibani & Ahangar, 2013; Pankhurst, 2006)). These stressors limit macroinvertebrates who provide critical ecosystem services such as fragmentation of trash and mixing of soil, which are vital for bringing organic matter into the soil. This organic matter can then be broken down by microbes and respired as CO2 or remain in the soil as a more stable form of carbon, promoting long-term carbon sequestration (Frouz, 2018; Nottingham et al., 2022). Increased soil carbon is vital for enhancing soil structure, nutrient retention, and water retention supporting both environmental sustainability and agricultural productivity (Magdoff & Van Es, 2009).
Background and Significance of the Research Question to drought risk, vulnerability, preparedness, or resilience:
Climate change poses a significant challenge to agriculture, with growing pressure to reduce emissions and adapt to climate extremes such as drought (Buck & Palumbo-Compton, 2022). The Australian Government’s net-zero emissions commitment by 2050 exacerbates this need for mitigation strategies, especially in major sectors like agriculture (DCCEEW, 2024). My project aligns with Australia’s climate commitments, by investigating how sugarcane farming practices impact soil macroinvertebrates and their role in carbon sequestration via the incorporation of sugar cane trash within soil. The research aims to provide insights into farming practices that maximise carbon sequestration as a potential climate mitigation strategy.
Additionally, the project is significant for drought resilience and overall soil health. Macroinvertebrates play a crucial role in soil health through their activities including the creation of pores for increased aeration and water infiltration as well as the incorporation of organic matter into the soil (Magdoff & Van Es, 2009; Brady & Weil, 2017). Both soil organic carbon (SOC) and soil organic matter (SOM) are essential for resilient soils due to their contributions to:
Macroinvertebrates and their essential contributions to SOC and SOM promote soils that are well-structured, nutrient-rich, moisture-retentive and stable, making them resilient to climate extremes like drought and improving agricultural productivity.
Academic and research experience relevant to the honours project:
I completed a Bachelor of Science, majoring in Zoology/Ecology, at James Cook University from 2021 to 2024, achieving a GPA of 6.38/7. During my degree, I undertook key subjects such as Tropical Entomology, Soil Properties and Processes for Management, and Field Studies in the Equatorial Tropics. Through my studies, I also assisted with entomology-focused PhD projects, providing me with invertebrate identification and sampling skills. In 2023, I received an Undergraduate Award for Excellence in Soil Science from Soil Science Australia’s QLD Branch, where I presented a project exploring the relationships between soil formation factors, soil properties, and soil fertility, which has provided me with a strong knowledge foundation for this research. Currently, I work casually for the Department of Agriculture, which has further developed my understanding of the interaction between soil health and agricultural productivity and provided me relevant skills such soil sampling. My passion for agricultural science and how it integrates with zoology/ecology, makes me a dedicated researcher for this project.
Principal Supervisor’s skills and experience in relation to this project topic:
Paul Nelson has extensive research experience in sustainable soil management in tropical agricultural systems, including sugarcane. He has supervised 4 PhDs, 3 MPhils and 13 Honours students to successful completion as primary advisor. He has published 5 books, 11 book chapters and 97 peer-reviewed scientific papers, with 8,200 citations. Of his papers, 51 were on soil carbon cycling and soil biology, including one on ants in rainforest soil. He was recently invited to write a book chapter on ‘Sustainable soil management in tropical agriculture’ (Nelson, 2023).
My name is Jorja Harvey, and I am studying a Science Honours, majoring in Zoology/Ecology at JCU in Cairns. I grew up in Newell, a beachside town north of Mossman, where I was fortunate to have an adventurous childhood filled with bike rides, creek swims, and bushwalks. Growing up immersed in nature, I developed a passion for biology, which led me to begin my university journey at UQ studying biomedicine. However, it wasn’t the right path for me, and after a 6-month deferral, I realised that the other side of biology was more fitting. I have always had a love for all animals, whether it was rescuing injured birds or running around with the bug catcher I had as a child. While my insect collection methods have evolved since then, my enthusiasm remains unchanged.
My project examines how sugarcane farming practices (insecticides and cultivation) affect invertebrates and impact soil carbon. I chose this project after developing a keen interest in soil science throughout my degree, with a love of understanding things from the ground up… literally. I also admire the complexity and diversity of soil whose importance is often overlooked. I am passionate about my project as it is a full-circle moment for me, allowing me to research the crop my hometown was built around. I also feel it is an important task to shift the focus from invertebrates as pests to recognising their essential roles. I hope my work will do justice the importance of soil and its many creepy crawly inhabitants.
Future Career Goals:
I aspire to continue agricultural research, emphasising the need for sustainable farming practices that maximise productivity without detriment to the environment. I look forward to deepening my knowledge and sharing my findings.
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