Australia is one of 186 countries to ratify the Paris Agreement; this agreement is on the reduction of climate change, limiting global warming to <2ºC warmer than pre-industrial global temperature, and ideally pursuing a change of no more than 1.5ºC (United Nations 2015, UNFCCC 2019). The two methods available for preventing enhanced global warming included preventing carbon emissions and sequestering carbon emissions. Soil contains a significant carbon pool, containing between two and three times as much carbon as the atmosphere (Minasny et al. 2017); the prevention of emissions and sequestration of carbon into soil via agricultural management has been strongly suggested as a method to mitigate against climate change (Minasny et al. 2017). Agriculture is a significant emissions sector in the Australian economy, releasing 13.1% of Australia’s emissions during the last accounting quarter (DEE 2018b); however, emissions from agriculture have decreased slightly since 1990, with most of the change driven by livestock management (DEE 2018b). Australia already has a framework for carbon sequestration in agricultural systems via the Emissions Reduction Fund (ERF) method for ‘measurement of soil carbon sequestration in agricultural systems’ (Commonwealth of Australia 2013, DEE 2018a). Few projects have successfully enacted this method however, due to a number of economic and administrative constraints (Burke 2016). Australia as whole also has a number of physical constraints to soil carbon sequestration as many of the soils contain naturally low carbon contents (i.e. arid soils) or are often water limited (Minasny et al. 2017). The largest losses of soil carbon due to agricultural management have occurred under conventional cropping with stubble burning, with >50% of carbon lost in the top 10 cm (Luo et al. 2010). This is similar to the global average of almost half of soil carbon lost due to agricultural activities (Paustian et al. 2000). There is an opportunity, therefore, for substantial carbon emissions sequestration through global agricultural best practice and a small opportunity for increased soil carbon sequestration in Australian agricultural areas.
Soil sustainability and security
Soil is essentially non-renewable and needs to be managed in a sustainable manner (Bui et al. 2010). As such, soil sustainability is the management and conservation of the natural resource base, and the orientation of technological and institutional change in such a manner as to ensure the attainment and continued satisfaction of human needs for present and future generations (United Nations 1998). Sustainable management is difficult however if human activities can place substantial demands on soil resilience, often leading to a decline in soil function and productivity over time (e.g. from poor agricultural practises) (Bennett and Cattle 2013). There are a number of soil characteristics that indicate soil condition, such as (Metcalfe and Bui 2017):
- carbon and nutrient contents,
- acidity (pH) and acidification trends,
- soil structure and porosity,
- topsoil thickness, and
Historically, poor soils management has led to significant losses in soil carbon, nutrients, and organic matter and subsequent negative changes in soil structure, acidity, and salinity (Bui et al. 2010, Metcalfe and Bui 2017). The retention of these positive characteristics and the prevention of soil degradation is therefore an important land management goal to ensure soil sustainability (Bui et al. 2010).
However, sustainable land management can only occur when the land’s capability is understood and the land is managed within that capability and although soils (NSW EPA 2015). It is also important to note that even though soils and their interactions underpin effectively all plant and animal production systems, our understanding of soils continues to be patchy (Burdon et al. 2017). Therefore although appropriate land management is vital for the sustainable use of soils, economic pressures can drive landholders into unsustainable production habits or prevent landholders from choosing more sustainable methods (NSW EPA 2015). These economic conflicts occur because systems that maximise yearly income are often not the same systems that maximise soil longevity (Bennett and Cattle 2013). Therefore, sustainable soil management requires approaches where long term soil condition is a core consideration (Campbell 2008).
A vital component of sustainable soil management and agricultural best practice is the availability of accurate and relevant soil information for landholders. In addition to the data generated by industry, research, and the government, landholders themselves generate data during their activities. Soil information is primarily in the form of geographical information systems (i.e. spatial data and mapping) and is spread between a large number of agencies, preventing efficient access and collaboration of interested parties. An important gap in Australia’s data infrastructure is therefore the lack of a single entity for the collection and curation of soils data.
Rather than a single-dimensional land assessment approach, such as land capability mapping of soil and landscape biophysical features, the Soil Security concept incudes consideration of other allied soil facets, including societal connections, education, policy, legislation, current land use, condition, and the economic and environmental value of our soils (Soil Science Australia 2018). Soil Security does not simply identify discrete soils, rather aspires to quantify additional stimuli which could result in soil becoming unsustainable, or not secure, and in quantifying this provide a framework for realising the potential for improved productivity, function, and ecosystem services. In this way, Soil Security is a broader concept than soil health, condition or quality.
Our food production in Australia is underpinned by the soil resource. Food exports are a significant sector in the Australian economy and indefinitely producing national and global food supplies will only be possible in agricultural systems that are managed sustainably (Orton et al. 2018). In this sector, industry driven sustainability goals are potentially an important driver in improving soil sustainability (VIC EPA 2018). However, it is important to realise that land that cannot be managed sustainably while being economically viable indicates that that land use is unsuitable for the capabilities of the site (Campbell 2008). Although both industry and individual landholders are responsible for enacting sustainability measures, governments also have a responsibility to support sustainable management through the provision of soil resources, community awareness, professional support, incentives, investment, and extension (Campbell 2008). Governments also have a responsibility to discourage unsustainable management by preventing inappropriate projects, and by maintaining regulations and compliance capabilities (Campbell 2008).
Burke, P. J. 2016. Undermined by adverse selection: Australia’s direct action abatement subsidies. Economic Papers: A journal of applied economics and policy 35:216-229.
Commonwealth of Australia. 2013. Emissions Reduction Fund green paper.
DEE. 2018a. Measurement of soil carbon sequestration in agricultural systems. Commonwealth of Australia – Department of Environment and Energy.
DEE. 2018b. Quarterly Update of Australia’s National Greenhouse Gas Inventory: September 2018 – Incorporating emissions from the NEM up to December 2018. Commonwealth of Australia – Department of Environment and Energy, Canberra.
Luo, Z., E. Wang, and O. J. Sun. 2010. Soil carbon change and its responses to agricultural practices in Australian agro-ecosystems: A review and synthesis. Geoderma 155:211-223.
Minasny, B., B. P. Malone, A. B. McBratney, D. A. Angers, D. Arrouays, A. Chambers, V. Chaplot, Z. S. Chen, K. Cheng, B. S. Das, D. J. Field, A. Gimona, C. B. Hedley, S. Y. Hong, B. Mandal, B. P. Marchant, M. Martin, B. G. McConkey, V. L. Mulder, S. O’Rourke, A. C. Richer-de-Forges, I. Odeh, J. Padarian, K. Paustian, G. Pan, L. Poggio, I. Savin, V. Stolbovoy, U. Stockmann, Y. Sulaeman, C. C. Tsui, T. G. Vågen, B. van Wesemael, and L. Winowiecki. 2017. Soil carbon 4 per mille. Geoderma 292:59-86.
Paustian, K., J. Six, and E. T. Elliott. 2000. Management options for reducing CO2 emissions from agricultural soils [J]. Biogeochemistry 25:430-440.
UNFCCC. 2019. Paris Agreement – Status of Ratification. United Nations Framework Convention on Climate Change.
United Nations. 2015. Paris Agreement. Page 16.
Soil Science Australia acknowledges the traditional owners of the land and pays its respects to their Elders, past, present and future.