The United Nations’ adoption of the 17 sustainable development goals (SDGs), under the 2030 Agenda for Sustainable Development, urged the scientific community to generate sound information with the aim of supporting planning and monitoring of socioeconomic development interlinking with environmental sustainability dimensions (UN 2015). SDGs 2, 3, 6, 11, 13, 14, and 15 refer to targets which commend direct consideration of soil resources. For instance, food security (SDGs 2 and 6), food safety (SDG 3), land-based nutrient pollution of the seas (SDG 14), urban development (SDG 11), and sustainability of terrestrial ecosystem services (SDG 15) are all depending on the provision of ecosystem services where soil properties and functions play a key role to deliver these. In particular, SDG target 15.3 on land degradation neutrality mentions, by 2030 to combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradation-neutral world. In addition, soils play an important role in mitigating and adapting to climate change (SDG 13). Further, SDGs 7 and 12 will indirectly rely on the availability of healthy soil resources. Regarding the remaining SDGs, linkages can be found to the sustainable management of soils to some extent (Keesstra et al. 2016).

The recent 48th session of the UN Statistical Commission revised the list of the global SDG indicators (UN 2017). The targets and indicators shown on Table 1 list soil properties and its functions. Currently, a soil-based indicator assigned to any of the soil-related SDGs is non-existent. The option of including such indicator is explicitly provided in the cases where disaggregation of indicators is relevant (UN 2017). In order to achieve the SDG goals based on soil resources, the relevance of including soil indicators from signaling to implementation stage is evident (Bouma and Montanarella 2016).

Table 1 Soil-related sustainable development goals and indicators
Full size table

The main question lies in what soil indicators should be considering and the monitoring methodologies behind. An analysis on the content of the SDGs and its indicators helps to clarify the level of integration of soils to these. There are five groups of SDGs and assigned indicators where soil plays a central role, namely:

  1. 1.

    explicitly include productivity (2.3, 2.4),

  2. 2.

    explicitly include soil degradation (15.3),

  3. 3.

    name soil in the SDG although no soil-based indicator has been proposed (3.9),

  4. 4.

    have direct relevance to soil resources with explicit reference to land resources but no reference to soil (11.3),

  5. 5.

    have direct relevance of soil to SDG without naming soil in SDG nor including soil-related SDG indicator (6.4, 6.5, 13.2, 14.1, 15.5).

Productivity is the soil property considered in several SDGs and incorporated into a broader concept of “agricultural productivity” term (SDGs 2.3, 2.4). Nevertheless, while agricultural productivity defines various factors and might also include components like animal husbandry and other segments, the fundamental factor of agricultural productivity is based on soil fertility (and climatic conditions). In addition, soil productivity loss is a central concept of land degradation (UNCCD 1994). Land degradation, in turn—apart from being a separate item among the SDGs (15.3)—refers also to the process leading to the reduction of soil water holding capacity and conductivity, loss of soil biodiversity, soil pollution, and/or nutrient load (SDGs 3.9, 6.4, 6.5, 14.1, 15.5). With regard to climate regulation (SDG 13.2), soil organic carbon (SOC) is considered the most relevant soil property.

To achieve the SDGs, there is an urgent need to assess and monitor the soil properties that impact soil productivity and the soil threats, with an emphasis on soil hydraulic properties, nutrient status, pollution, soil biodiversity, and SOC changes. An option is through the assessment of soil properties in the minimum datasets (Doran and Parkin 1996; Li et al. 2007). These include physical, chemical, and biological indicators of which standardized assessments and regular monitoring are carried out (Nortcliff 2002). However, current monitoring systems are not fully prepared to provide complete required information (Morvan et al. 2008; Tóth et al. 2017). Soil hydraulic properties (water retention and conductivity) and nutrient cycling are key indicators for soil productivity. In addition, vertical soil properties (horizons), underlying hydrology and topography, are also important. Soil texture on the other hand is the most basic soil physical attribute which determines hydraulic properties. However, as it remains unaltered over the medium term, monitoring focuses rather on other relevant attributes (i.e., OC, bulk density, salinity). These likewise will influence on the soil water status. OC plays a central role not only in soil water characteristics and climate control but also in the nutrient status of soil. Contamination and soil biodiversity remain separate for which the monitoring programs will need to include. Nevertheless, if these aspects of soil quality can be assessed and monitored, much of the SDGs can indeed be followed. Table 1 suggests the most relevant soil physical, chemical, and biological indicators that can potentially be applied within the framework of the SDG indicators.

Efforts are being made for improving soil monitoring systems, such as the European Union’s work gathering information on soil bulk density and soil biodiversity (Fernández-Ugalde et al. 2016) along with the potential of mass data gathering and big data on morphological properties and OC status. These are examples that will help enable the use of soil indicators to support the monitoring of the SDGs. In addition, there needs to be established a global indicator framework for monitoring progress in protecting soil resources and soil-based sustainable development.

The spatial extent of global and regional soil quality assets has to be considered and integrated into policies ranging from sustainable urbanization to agricultural development. Soil functions and degradation threats are manifold, and soil indicators are diverse. Monitoring soil and land changes for all these considerations is a challenge which needs to be addressed. The SDGs help to streamline the efforts of soil monitoring programs, which, combined with the new sources of soil information and extensive application of modern technological solutions can provide the needed data and information. Additionally, harmonization between different sampling and monitoring programs as well as between measurement standards and protocols (Nortcliff 2002; Morvan et al. 2008) still needs to be completed. Current efforts towards global harmonization of soil information, e.g., the upcoming global soil organic carbon map by the Global Soil Partnership (GSP FAO and ITPS 2017) remarks the fulfillment of these requirements being feasible. The next steps are to apply this valuable knowledge to fully align and support the achievement of the SDGs.