Soil carbon storage is a vital ecosystem service, resulting from interactions of ecological processes. Human activities affecting these processes can lead to carbon loss or improved storage.
Organic matter is a key component of soil that affects its physical, chemical, and biological properties, contributing greatly to its proper functioning on which human societies depend. Benefits of soil organic matter (SOM) include improvement of soil quality through increased retention of water and nutrients, resulting in greater productivity of plants in natural environments and agricultural settings. SOM improves soil structure and reduces erosion, leading to improved water quality in groundwater and surface waters, and ultimately to increased food security and decreased negative impacts to ecosystems. Since the beginnings of recorded history, societies have understood that human activities can deplete soil productivity and the ability to produce food (McNeill and Winiwarter 2004). Only in recent history has the understanding of soil productivity been tied to SOM levels, with the depletion of SOM stocks often leading to large-scale impacts on whole ecosystems as well as the entire planet. For example, destruction of rainforests that hold a significant amount of the carbon stored in terrestrial ecosystems contributes significantly to rising atmospheric carbon dioxide (CO2) levels linked to climate change, while reductions in SOM levels from soil disturbance from mining can impact infiltration of rainfall and the storage of soil moisture important for flood mitigation. Soil disturbance also leads to increased erosion and nutrient leaching from soils, which have led to eutrophication and resultant algal blooms within inland aquatic and coastal ecosystems, ultimately resulting in dead zones in the ocean (Fig. 1). Restoration of organic matter levels in soil requires an understanding of the ecological processes important for SOM storage. Proper restoration techniques can help restore terrestrial ecosystem functions.