Depletion and recovery of soil organic matter: ecological, economic and social implications

Over the past decades, urbanization, industrialization and unsustainable management have impaired soil fertility and ecosystem functioning, thereby affecting ecological stability and economic development. The mechanistic coupling between pressures and effects lies in the loss of soil organic matter (SOM), which directly and indirectly controls the vast majority of soil properties and the functioning of the soil ecosystem. From the functions SOM exerts in the soil ecosystem, to the consequences of its depletion and the possibilities it offers for ecological restoration, this concise opinion offers a perspective on the multifaceted roles of SOM in sustaining ecosystem functioning and the services it generates. Indeed, SOM plays crucial roles in supporting soil long-term fertility and the provision of ecosystem services, such as food, water, genetic, medical and biochemical resources, religious, cultural and recreational values, as well as sequestration of carbon and regulation of climate. These roles foster the view of SOM as an ideal proxy for soil quality and health, and justify the interest in acting on SOM as a mean of enhancing the sustainability and effectiveness of ecological restoration projects. The improvement of SOM to favor the onset of proper ecological dynamics in heavily degraded ecosystems, such as urban, industrial and agricultural soils, can be also coupled to the recovery of useful organic matter from wastes, integrating ecosystem restoration within waste management and sustainable circular economy strategies. Since, ultimately, the sustainability of our civilization depends upon proper ecological dynamics, soil quality rises to a topic of public concern and this opinion aims at providing a reference point of view on the intertwined implications of its preservation on the ecological, economic and social spheres.