Menu
Research Questions/Objectives:
Brief Description of the Project:
The Honours project will be nested within a project funding by the Leverhulme Centre for Climate Change Mitigation (LC3M), in which James Cook University (JCU) is conducting enhanced weathering field trials on tropical soils near in Far North Queensland. A relationship has been found between annual mean temperatures and rates of CO2 consumption, with warm and humid climates found to best suit the process (Li et al., 2016; Strefler et al., 2018). This project provides an avenue for data collection through soil, biomass, and leachate analysis. Chemical weathering of rocks is well understood, however, understanding precisely how much carbon originating from weathering processes has influence on leachate alkalinity, not influenced by other factors, remains open to further research.
Changes in alkalinity between different basalt and liming treatments can be observed through increased bicarbonate concentrations found in leachate. Measuring dissolved organic carbon, using the Picarro Cavity Ring-Down Spectroscopy (CRDS) method (Piccaro, 2022), will precisely quantify the 12C and 13C isotopes being derived through weathering processes. This will determine the extent that carbon influences alkalinity as bicarbonate, and how much CO2 is sequestered through enhanced weathering by comparing different field trial treatments. Four plots will be treated with 50 t/ha of crushed basalt and four as control plots (untreated). Within each plot, one subplot will be treated with 2.5 t/ha of agricultural lime and another control sub-plot (untreated).
The field trial soil type is a naturally slightly acidic Kandosol and the use of nitrogen fertilisers brings additional acidity into sugarcane production (Kalkhoran et al., 2020). Low pH lowers the cation exchange capacity (CEC) of soils, reduces nutrient availability to plants and pH values below 5.5 can bring Al into solution (Al3+), which is toxic to plants (Brady & Weil, 2017). Therefore, the bicarbonate produced through enhanced weathering, and added with lime is predicted to produce a net alkalinisation of the soil and leachate. This increase in pH will improve soil health and alleviate soil constraints, improving crop yield and plant vigour, and consequently build drought resilience (Schneider et al., 2020).
Background and Significance of the Research Question to drought risk, vulnerability, preparedness, or resilience: Societies’ urgent need for climate change mitigation has led to growing interest in negative emissions technology development to accompany emissions reduction strategies (Haszeldine et al., 2018). Environmental concerns often accompany such initiatives due to the widespread negative externalities resulting from human activities (Rockström et al., 2009). Australian farmers and rural communities, often confronted with these issues firsthand, are increasingly concerned about the impacts of climate change on crop yields and environmental degradation, and are searching for adaptation strategies and methods to build drought resilience (Kiem & Austin, 2013).
Enhanced weathering is the chemical weathering of rocks sped up through the spreading of crushed silicate rocks, often over agricultural lands (Beerling et al., 2018). The increased surface area of finer rock particles is important if weathering rates are sufficient enough to contribute to net CO2 drawdown (Rinder & von Hagke, 2021). The CO2 converted to bicarbonate will leach from the soil, enter waterways, and eventuate in the ocean as carbonate. The enhanced weathering process (in this project) of crushed basalt, has multiple positive environmental externalities:
Academic and research experience relevant to the honours project: I studied a Bachelor of Environmental Practice at James Cook University between 2019 and 2022, majoring in land and water management and corporate environmental management achieving an overall GPA of 6.75/7. During my studies, I undertook a work placement with the Queensland Department of Resources Land Resource Assessment division, developing high resolution soil mapping through electromagnetic induction (EMI) and soil profile describing across the Babinda swamp catchment. The purpose of the research was to advise sugarcane producers on nutrient use efficiency and nitrogen loss mitigation strategies. In addition to this, I contributed to an earlier phase of the LC3M enhanced weathering project, conducting soil and water sampling and EMI mapping of the field trial site. In September 2022, I was awarded the role as the research officer on phase two of this project. The position involves coordinating all aspects of field work, data collection and interpretation of results during the updated phase of the field trial, under the supervision of A/Prof Paul Nelson.
Principal Supervisor’s skills and experience in relation to this project topic: Paul Nelson is a soil scientist with a 21-year record of research project leadership, often in collaboration with industry. He has led projects on carbon cycling in soils and catchments, nutrient cycling and management, GHG emissions, and soil chemistry in tropical agriculture in Queensland, Papua New Guinea and Indonesia, including the project in collaboration with the LC3M that led to this proposal. Since joining academia in 2004 he has supervised 10 PhD (4 as Primary Advisor), 7 MPhil (3 as Primary Advisor) and 11 Honours candidates to completion.
References
Beerling, D. J., Leake, J. R., Long, S. P., Scholes, J. D., Ton, J., Nelson, P. N., Bird, M., Kantzas, E., Taylor, L. L., Sarkar, B., Kelland, M., DeLucia, E., Kantola, I., Müller, C., Rau, G., & Hansen, J. (2018). Farming with crops and rocks to address global climate, food and soil security. Nature plants, 4(3), 138-147. https://doi.org/10.1038/s41477-018-0108-y
Brady, N. C., & Weil, R. R. (2017). The nature and properties of soils (Fifteenth edition. ed.). Pearson Education Limited.
Haszeldine, R. S., Flude, S., Johnson, G., & Scott, V. (2018). Negative emissions technologies and carbon capture and storage to achieve the Paris Agreement commitments. Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences, 376(2119), 20160447-20160447. https://doi.org/10.1098/rsta.2016.0447
Kalkhoran, S. S., Pannell, D., Thamo, T., Polyakov, M., & White, B. (2020). Optimal lime rates for soil acidity mitigation: impacts of crop choice and nitrogen fertiliser in Western Australia. Crop and pasture science, 71(1), 36-46. https://doi.org/10.1071/CP19101
Kelland, M. E., Wade, P. W., Lewis, A. L., Taylor, L. L., Sarkar, B., Andrews, M. G., Lomas, M. R., Cotton, T. E. A., Kemp, S. J., James, R. H., Pearce, C. R., Hartley, S. E., Hodson, M. E., Leake, J. R., Banwart, S. A., & Beerling, D. J. (2020). Increased yield and CO2 sequestration potential with the C4 cereal Sorghum bicolor cultivated in basaltic rock dust‐amended agricultural soil. Global Change Biology, 26(6), 3658-3676. https://doi.org/10.1111/gcb.15089
Kiem, A. S., & Austin, E. K. (2013). Drought and the future of rural communities: Opportunities and challenges for climate change adaptation in regional Victoria, Australia. Global environmental change, 23(5), 1307-1316. https://doi.org/10.1016/j.gloenvcha.2013.06.003
Li, G., Hartmann, J., Derry, L. A., West, A. J., You, C.-F., Long, X., Zhan, T., Li, L., Li, G., Qiu, W., Li, T., Liu, L., Chen, Y., Ji, J., Zhao, L., & Chen, J. (2016). Temperature dependence of basalt weathering. Earth and planetary science letters, 443, 59-69. https://doi.org/10.1016/j.epsl.2016.03.015
Page, K. L., Allen, D. E., Dalal, R. C., & Slattery, W. (2009). Processes and magnitude of CO₂, CH₄, and N₂O fluxes from liming of Australian acidic soils: a review. Australian journal of soil research, 47(8), 747-762.
Piccaro. (2022). Cavity Ring-Down Spectroscopy (CRDS). Picarro, Inc. Retrieved 17 November from https://www.picarro.com/company/technology/crds
Rinder, T., & von Hagke, C. (2021). The influence of particle size on the potential of enhanced basalt weathering for carbon dioxide removal – Insights from a regional assessment. Journal of cleaner production, 315, 128178. https://doi.org/10.1016/j.jclepro.2021.128178
Rockström, J., Steffen, W., Noone, K., & Scheffer, M. (2009). A safe operating space for humanity. Nature (London), 461(7263), 472-475. https://doi.org/10.1038/461472a
Schneider, R., Morreale, S., Li, Z., Menzies Pluer, E., Kurtz, K., Ni, X., Wang, C., Li, C., & Van Es, H. (2020). Restoring soil health to reduce irrigation demand and buffer the impacts of drought. Frontiers of Agricultural Science and Engineering, 7(3), 339-346. https://doi.org/10.15302/J-FASE-2020348
Strefler, J., Amann, T., Bauer, N., Kriegler, E., & Hartmann, J. (2018). Potential and costs of carbon dioxide removal by enhanced weathering of rocks. Environmental research letters, 13(3), 34010. https://doi.org/10.1088/1748-9326/aaa9c4
Background
The impacts of climate change are here, and society must look beyond reducing CO2 emissions to achieve effective, large-scale climate change mitigation (Gasser et al., 2015). The enhanced weathering (EW) of silicate rocks such as basalt is being studied as a potential negative emissions technology (Brantley et al., 2023). EW involves spreading crushed silicate minerals over large areas of land, where the increased surface area raises potential chemical weathering and subsequent generation of bicarbonate from dissolved CO2. Bicarbonate leaches into the groundwater, then travels through rivers into the ocean where it eventually precipitates as carbonate, representing long term storage (Figure 1) (Beerling et al., 2018). There are several benefits attributed to the EW of basalt, including a natural liming effect from the bicarbonate, lifting pH, and increasing nutrient availability to plants (Beerling, 2017; Strefler et al., 2018).
The addition of beneficial elements such as silicon, improves sugarcane tolerance to drought stress (Verma et al., 2020). Modelling has suggested significant rates of CO2 removal through EW, and tropical regions offer suitable environmental conditions. However, CO2 removal through EW field trials remain inconclusive and low soil pH has been identified as a factor potentially limiting to the process (Dietzen & Rosing, 2023). This study aimed to quantify CO2 removal through the EW of basalt under sugarcane in an acidic soil, incorporating a liming treatment to measure the effect of soil pH amelioration on CO2 removal. Furthermore, differences between treatments in soil pH and silicon concentrations, and uptake by plants was measured and reported.
Trial overview
This study was a part of a larger project, with annual basalt applications. The field trial for 2022/23 consisted of two basalt treatments (+/-) assigned to main plots (as previous years) and two lime treatments (+/-) assigned to subplots. Prior to the wet season, 32 drainage fluxmeters were installed in the row and interrow of each subplot, and leachate was sampled following rain events using a 12V vacuum pump (Figure 2). Leachate samples were immediately analysed for alkalinity (bicarbonate) using an auto titrator. Soil and plant samples were taken prior to the wet season with results relevant to drought resilience also reported here.
Key findings
Basalt and/or lime treatment increased mean bicarbonate production and leaching, but the effect was not significant (Figure 3). There was however a significant effect of sampling location, i.e. row versus inter-row (p=0.02) and the interaction between sampling location and lime (p=0.026), with higher leached cumulative bicarbonate measured in the interrow, especially when lime was applied. The amount of leached bicarbonate was low in all treatments, especially compared to potential CO2 removal modelling for this trial (Reershemius et al., 2023).
Silicon concentrations were significantly higher in the topsoil (0-10 cm) (p <0.001) and cane leaves (p=0.004) in basalt-treated plots (Figure 4).
Silicon concentrations were significantly higher in the topsoil (0-10 cm) (p <0.001) and cane leaves (p=0.004) in basalt-treated plots (Figure 4).
Implications for drought resilience
Although drought occurs naturally in Australia, climate change is increasing the frequency and severity of drought events (Cai et al., 2014; Malik et al., 2021; Mukherjee et al., 2018). Enhanced weathering research primarily exists for its potential as a negative emissions technology. This trial found no significant effect of basalt or lime treatments on cumulative leached bicarbonate (CO2 removal) throughout the 2022/2023 wet season. Furthermore, CO2 removal values in all treatments were negligible compared to basalt weathering rates estimated in this trial (Reershemius et al., 2023). It should be considered that these findings followed 5 annual basalt applications, however, only one season of leachate analysis. Further wet season leachate analysis would benefit the dataset. Notwithstanding this, significant co-benefits were found from the enhanced weathering of basalt.
Silicon concentrations increased significantly from basalt application in both topsoil and cane leaves. Silicon fertilisation improves plant vigour and the ability to withstand exogenic stresses such as drought (Coskun et al., 2016; Guerriero et al., 2020). In addition to drought resistance, improved crop yield and nutrient uptake in plants has been attributed to silicon application (Coskun et al., 2016; Malik et al., 2021; Rizwan et al., 2015). Therefore, silicon increases measured here show promise for increasing drought resilience in sugarcane through enhanced weathering of basalt.
Soil pH was also significantly higher in basalt treated plots. The neutralising effect of basalt in acidic soils offers to increase soil pH to levels more favourable to sugarcane production. In addition, reducing agricultural lime requirements reduces CO2 emissions from its application (West & McBride, 2005). Increasing soil pH and silicon benefits soil health, key to the long-term drought resilience of crops through reduced irrigation requirements and increasing plant growth and crop yield (Neina, 2019; Schneider et al., 2020).
References
The impacts of climate change are here, and society must look beyond reducing CO2 emissions to achieve effective climate change mitigation. Enhanced weathering is a potential negative emissions technology where crushed silicate minerals are spread over large areas of land, and chemical weathering generates bicarbonate, removing CO2. Several benefits are attributed to enhanced weathering, including a liming effect from the bicarbonate, and increased nutrient availability to plants. The addition of beneficial elements such as silicon is likely to improve sugarcane tolerance to drought stress. This field trial has received annual basalt applications (0 and 50t/ha) since 2018 and a lime application (0 and 2.5 t/ha) prior to the 2022/23 wet season. Drainage fluxmeters were installed, and leachate was sampled to measure bicarbonate flux during the wet season. Soil and plant samples from 2022 were analysed for their nutrient contents. Leached bicarbonate flux was slightly higher in the basalt- and lime-treated plots but the effect was not significant, and all values were very small. Bicarbonate flux was significantly higher in the inter-row than in the row (p=0.02) especially where lime was also applied (p=0.026 for location*lime interaction). Silicon was higher in the topsoil (0-10 cm) (p <0.001) and cane leaves (p=0.004), and soil pH was higher at 0-10 cm (p<0.001) and 10-25 cm (p<0.001) depths in basalt-treated plots, indicating a liming effect. Increasing soil pH and nutrient availability from basalt is favourable to sugarcane production and likely to increase drought stress tolerance and resilience of plants. Further research is required to determine reasons for low leached bicarbonate from enhanced weathering here. However, benefits to producers are immediate and should be considered when rolling out further field trials.
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.
ANCHOR HERE TO MILESTONE 1 AND MILESTONE 2
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.
people can just keep scrolling for each of the
