Soil organic carbon as a relevant indicator for the SDGs?

An earthworm in its natural habitat.Click to enlarge
An earthworm in its natural habitat.
Source: S. Marahrens / Umweltbundesamt

Soil organic carbon (SOC) is associated with many critical soil-derived ecosystem services. But what happens if the SOC content is decreasing? A decline in SOC stock may indicate degradation or even loss of land and soil. Therefore, it is currently discussed whether the SOC stock might play an important role in the realisation of the global Sustainable Development Goals.

Soil organic carbon supports critically important soil-derived ecosystem services, as water filtration, soil stability, nutrient conservation, and pollutant denaturing and immobilization. Moreover, it plays an important role in climate protection – the SOC stock for soil profiles of the ice-free land area is currently estimated at about 3000 gigatons carbon.

But what happens if the SOC content is decreasing? A decline in SOC stock may indicate degradation or even loss of land and soil. These include in particular wind and water erosion, compaction, waterlogging, decreased nutrient availability, and loss of soil biodiversity resulting among others in decreased plant growth and yields.

Therefore, the SOC stock is discussed as possible indicator for the implementation of the Sustainable Development Goals (SDGs).

The 17 SDGs and related 169 targets, adopted by the United Nations in September 2015, aim to end poverty, protect the planet, and to ensure prosperity for all. Due to their various functions, land and soil are addressed by several SDGs and targets. Explicitly, SDG 15.3 targets to strive to achieve a “land degradation neutral world”. 

The report „Soil Organic Carbon – An Appropriate Indicator to Monitor Trends of Land and Soil Degradation within the SDG Framework?“ takes a close look at the importance of the SOC and its potential as indicator for land and soil degradation. Furthermore, it illustrates challenges to be met and conditions to be created in order to establish the SOC stock as a globally relevant and feasible indicator for the implementation of the SDGs.