Soil carbon : introduction, importance, status, threat, and mitigation

Soils represent a massive stock of terrestrial organic carbon (C) and act both as a buffer against atmospheric CO2 increase and as a potential sink for additional C depending on the balance between photosynthesis, the respiration of decomposer organisms, and stabilization of C in soil. Soil organic matter comprising of approximately 58% of soil organic carbon (SOC) is the basis of many soil functions and ecosystem services, including provision of food and fiber, habitats for biodiversity, climate regulation, water filtration and purification, and human heritage. The importance of SOC in maintaining the capacity of soils to perform multiple ecosystem processes has been recognized by farmers in all ancient civilizations. Managing SOC through sustainable agricultural and land use practices has become a widely acknowledged strategy to combat land degradation and desertification, as well as to provide food security in a changing climate. Several national and international efforts have been initiated to implement practical programs of SOC management and the types of farming methods used to promote it. Enhancing and sustaining SOC to increase soil health is also pertinent to advancing Sustainable Development goals of the U.N. including no hunger, good health and well-being, clean water, climate action, and life on land. This chapter briefly highlights the importance of SOC for ecosystem services, national and intergovernmental policies, while also identifying opportunities to increase SOC to address multiple global challenges.