Securing our soil

Abstract

Through the recognition and interplay of biochemicophysical (pedologic and edaphic), economic, social and policy dimensions, soil security is a wider and more integrative concept than previous policy- and management-focused notions such as soil conservation, soil care, soil quality, soil health and soil protection. It is the soil homolog of food, water and energy security. In this way, global significance of soil for sustainable development is emphasized. Through the five dimensions of soil security, the value of soil in addressing at least six of the current global existential challenges is formulated, and the intrinsic import of soil security as an equally essential worldwide pragmatic requirement is resolved. The immediate quest is for a multidisciplinary understanding to qualify and quantify the five dimensions effectively and efficiently so that the security of soil in fields, catchments or watersheds, regions, countries, continents and globally can be measured, maintained or improved through appropriate management and policy, and monitored on an ongoing basis.

Key words:

• capability
• capital
• codification
• condition
• connectivity

INTRODUCTION

The importance of soil to support the global increase in demand for food, water and energy is well known to soil science, as is its role in providing ecosystem services that minimizes the environmental impacts of climate change and to maintain the world’s biodiversity. These can be summarized into six existential environmental challenges, being food security, water security, energy security, climate change abatement, biodiversity protection and supporting human health (Bouma and McBratney 2013). Successfully framing soil within these challenges will require engaging those outside the soil science community so that soil is routinely part of the conversation, and to do this a new concept of “Soil Security” was launched at the 20^th World Congress of Soil Science (WCSS) in Jeju, Korea.

With the population predicted to exceed over 9 billion by 2050 (Godfray et al. 2010), some suggest it will be greater than the world’s capacity to produce food in a sustainable way, and will place immense pressure on the availability and distribution of water (Rockström et al. 2009). Access to good-quality food will need to be combined with sufficient knowledge and adoption of technologies to maintain good soil conservation practices (Fedoroff et al. 2010). This will require continued efforts to increase yields, and being able to source soil amendments that are used to improve soil fertility (Cordell et al. 2009; Pretty et al. 2011). As well as availability, the growing population will need the resources to access available food and the knowledge of basic nutrition (Pinstrup-Anderson 2009; Godfray et al. 2010). Increased food production will put more pressure on global water security, with increased harvesting of water from rivers and dams—the so-called “blue water” (Anonymous 2008). To mitigate this, research continues with a focus on improving our understanding of soil–water–plant interactions to increase the amount of water that is transpired, identified as “green water,” with the aim of improving water-use efficiencies (Falkenmark and Rockström 2006; Morison et al. 2008; Rockström et al. 2009). The allocation of land to produce biofuels, and competitive exploitation to access subsurface energy resources (e.g., coal seam gas), are a further impact on the soil resource (Sovacool 2007; Tilman et al. 2009). Similarly, the use of renewable resources and maintaining emissions from energy that does not exceed assimilation capacities, including increased carbon storage in soil, will affect future climate change and its impact on agronomic productivity (Lal 2010; Janzen et al. 2011).

Soil degradation processes such as erosion, fertility loss, salinity and acidification, soil carbon decline and compaction are recognized threats to soil (CEC 2006) that compromise the ecosystem services that soil provides (Robinson et al. 2009), which are broadly described as supporting, provisioning, regulating and cultural services (McBratney et al. 2014). The supporting services provided by soil include support for plants, delivery of nutrients, and a gene pool. Its role in the hydrological cycle and as a repository for waste are examples of regulating services, while the provisioning services of soil are exemplified by its excavation for building materials, while archeological preservation and heritage are cultural services of the soil (Robinson et al. 2009). The newly established Global Biodiversity Soil Initiative (http://www.globalsoilbiodiversity.org/) moves beyond recognizing that soil supports the largest diversity of species, to recognizing that it also houses that largest gene pool. The diversity of species contributes to the formation of soil itself, as well as nutrient and water efficiency, transfer of energy and matter, and protection against soil-borne disease (Filip 2002; Lavelle et al. 2006; Brussaard et al. 2007). This gene pool will contribute to the future development of products that sustain human health (Brevik and Burgess 2013).

SOIL SECURITY

Without secure soil, the ability to secure the supply of food, fiber and water, to maintain biodiversity, and to produce renewable sources of energy is compromised, and this is why soil should be promoted to the status of the seventh global existential challenge (Koch et al. 2013). To do this, soil security is concerned with maintaining and improving the world’s soil resource to produce food, fiber and fresh water, and to maintain the biodiversity and ecosystem services that contribute to human health (McBratney et al. 2014), and in this definition security is used in the same sense as for food, water and energy. This concept is also similar to the existing concepts of soil quality, soil health and soil protection (Doran and Zeiss 2000; Karlen et al. 2001; Bouma and Droogers 2007). At the plenary session of the 20^th WCSS, Alex McBratney, from Sydney University, said “that to action this definition will require the development of five dimensions that frame soil security.” The dimensions of “capability” and “condition” are concerned with the biophysical challenges. These two dimensions have long been researched and discussed, forming the core business of soil science.

The capability of a soil refers to its potential functionality, and recognizes that soils themselves are multi-functional. The question that capability answers is, “What can this soil do?” This dimension is intrinsically linked to the long history of land evaluation (FAO 1976; Bouma et al. 2012) but, unlike land quality which includes geomorphology and climate in its evaluation, capability requires an explicit and transparent evaluation of the soil qualities reported independently. As the concept of soil security matures there is a need to recognize a reference state that exemplifies what this soil is capable of and to which the current condition of the soil can be compared. Using the logic that frames land evaluation (Rossiter 1996), the development of a reference state is possible and will enable predictions of soil behavior under different management, which underpins decisions made by land managers, and policy development. The condition of the soil is concerned with the current state, and refers to the shift in capability compared to the reference state (McBratney et al. 2014). Essentially, the question that condition asks is, “Can the soil do this?” and therefore is monofunctional. As with capability, the condition of the soil will change with changing management, but unlike capability these changes will occur within human timescales. Good management of the soil condition for poorly capable soils can produce increases in yield, while, equally, poor management of highly capable soils may compromise the yield potential (Tugel et al. 2005). As with soil quality and health, the soil condition can be assessed using a set of quickly varying and, more often than not, manageable indicators, which are linked to soil function (Nortcliff 2002). Professor Bouma of Wageningen University in the Netherlands took the challenge of illustrating the dimensions of capability and condition at the 20^th WCSS using examples from the Netherlands and Africa, where knowing what the soil is capable of is essential when developing government regulations and also when supporting local farmer and business development. The success of these approaches also relied on routine assessment of the soil’s condition to monitor any undesirable outcomes (Bouma et al. 2011).

As soil security is a concept towards the sustainability of the soil resource, we need to consider more than just the biophysical dimensions (McBratney et al. 2014). Often recognized as everyone’s problem, but not the central concern of soil scientists, are the socioeconomic challenges faced when soil is not secured. Soil security frames this by demanding that there is a need to place a value on the soil so the soil’s capital can be estimated, and how this is affected by people’s connection with the soil, as well as the need for good policy to secure soil against further degradation. Placing a value on “things” that contribute to human well-being avoids neglect of the resource, and ensures its contribution to any decision-making process (Robinson et al. 2009). The soil’s natural capital is determined by its compositional state, or stocks, which affect the functions provided by the soil as an ecosystem service (Dominati et al. 2010). The stocks are outlined in Table 1, which demonstrates that the economic value of the stock may not always be related to the benefit. Anna van Paddenburg from the Global Green Growth Institute in Jakarta described, at the 20^th WCSS, how a change in focus to include valuing natural resources resulted in synergies that both support agricultural production and maintain the surrounding ecosystem to support the provision of wildlife and water quality (van Paddenburg et al. 2012). How people are connected with the soil equally will impact on how soil is valued and therefore secured. The connectivity dimension in part is concerned with whether the person who manages soil has the right knowledge and resources to manage the soil to its capability. This relies on education opportunities for good soil knowledge that is also integrated with other disciplines, policy experts and users of soil itself (Field et al. 2011). The opportunity to share knowledge on soil into the future relies on trained individuals who not only have “good hard soil knowledge but the social intelligence” to provide relevant soil advice (Bouma et al. 2011). It is expected that these “knowledge brokers” would facilitate collaboration between researchers, the education community and the end-users of soil (Stockmann et al. 2013). “How society is connected to the soil” some might argue is an even more important aspect of soil security. While soil is enmeshed in the past and future of our society (Janzen et al. 2011), soil is almost invisible to those outside of the soil science community. While concepts such as “terroir” exist, linking the value of a wine product with the soil, this does not exist for most other products consumed by society. To make soil secure there is a need to have mechanisms that allow people to make a connection between soil and its products, have the ability to feedback their opinions about these products to the managers of soil. (McBratney et al. 2014).

Table 1 Natural stocks of soil that contribute to placing a value on the ecosystem service (from McBratney et al. 2014)

Type of service	Indicator	Economic value
MASS
Solid	Inorganic material
	Mineral stock	Cost of building materials
	Nutrient stock	Replacement costs of fertilizer
	Organic material
	Carbon stocks	Carbon offsets
	Organisms	Medicines
Liquid	Soil water content	Irrigation and fresh water supplies
Gas	Soil air	?
ENERGY
Thermal energy	Soil temperature	?
Biomass energy	Soil biomass	Relative to carbon, with a premium for diversity
ORGANIZATION
Physicochemical structure	Soil physicochemical organization, soil structure	Value of increased water holding capacity
Biotic structure	Biological population organization, food webs and biodiversity	Diversity premium—a multiplier for carbon—value of multiplier 2–5
Spatiotemporal structure	Connectivity, patches and gradients	?

This knowledge, along with the final dimension of codification, which is concerned with developing good public policy that is synergistic with the other dimensions, will contribute to securing soil. Robert Hill, a former Senator and Environment Minster, brought the policy agenda to the discussion at the 20^th WCSS, as well as the need for a clear focused message around the role of soil in securing the future. Soil is sporadically included in regional and national policy and legislation (Koch et al. 2013). While soil has been discussed in the global agenda, e.g., RIO+20, the challenge to have soil explicitly recognized in international political and policy arrangements continues to be elusive. This is often achieved when a clear message is developed, focusing on a single indicator for change. Senator Hill noted that, considering the recent focus of society on carbon, we might adopt soil carbon as an indicator of soil change. While universal indicators are not advocated generally for soil, carbon plays in many of the soil functions and there is research demonstrating that soil carbon below critical limits will compromise the soil condition (Stockmann et al. 2013).

CONCLUSIONS

Soil security is a new, wide-ranging, multi-dimensional, multidisciplinary concept that has antecedence in notions such as soil conservation, care, quality, health and protection.

• It is homologous to the constructs of food, water, energy and climate security.

• The five dimensions cover biochemicophysical, economic, social and policy considerations.

The immediate emphasis is multidisciplinary work on quantifying the dimensions and initiating measurement for various spatial and temporal extents.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the support of the Australian Research Council.