Role of carbon cycle in soil productivity and carbon fluxes under changing climate

Soils are the resources most vulnerable to climate change but the main reservoir for carbon. They contain more carbon than the atmosphere and terrestrial vegetation (crops and forests). Organic carbon of the soil is dynamic in nature and anthropogenic activities can turn it into either a net sink or a net source of atmospheric greenhouse gases through different activities. After carbon enters the soil in the form of organic material from soil flora and fauna, it can persist in it for decades, centuries, or even millennia. Eventually, soil organic carbon can be lost back into the atmosphere in the form of carbon dioxide, become material of the soil that is eroded, or be dissolved in the form of organic carbon and runoff into the oceans and rivers. This is called the carbon cycle which decides the soil health, fertility, and productivity to assure greater benefits for the well-being of humans, production of food, and regulation of climate. As a soil health indicator, soil organic carbon plays an important part for its input toward the production of food, and for the adaptation and mitigation strategies to achieve the development goals of sustainability for the change in climate. Nutrients are provided to plants by soil organic carbon content and also the availability of water improves by the organic carbon, which enhances the fertility of the soil and in turn the productivity of food also improves. Furthermore, soil organic carbon promotes the formation of soil aggregates that improves the stability of the structure of the soil, which combines with the level of porosity and assures enough infiltration and aeration of water to support the growth of plants. This chapter provides literature about the carbon cycle, its importance in soil productivity, and factors affecting carbon fluxes to the soil and atmospheric environment.