**3. Understanding role of SOC and carbon management practices**

Soil Organic carbon (SOC) is the controlling factor for soils physical, chemical, biological and ecological functionality and wellbeing. Not only soil's health and productive capacity but soil carbon can also mitigate hazardous climate change. Quality and quantity of SOC; its dynamics/turnover is the main governing factor of soils ecosystem functions. A huge loss (50 to 75% and with magnitude of loss of around 30 to 60 Mg C/ha) of antecedent soil C pool has occurred due to land conversion, cultivation and erosion associated with it in most agricultural ecosystems [12]. Generally, agricultural soils contain considerably less SOC than soils under natural vegetation, hence, these lands are deprived of C than their ecological potential.

Carbon management practices (CMP) aim to sequester i.e., to capture and secure storage of carbon that would otherwise be emitted to, or remain, in the atmosphere. In other words, CMP is enhancing and/or maintaining soil carbon


#### **Table 3.**

*Mechanism of increasing MRT of SOC for its stabilisation.*

not allowing it to escape out to the atmosphere. In agricultural fields, addition of biomass carbon and organic manure is a direct approach but stabilisation of the soil carbon is through its physico-chemical property. Physical mechanism includes formation of organo-mineral complexes, encapsulation in microaggregates within macroaggregates, deeper placement of carbon in the soil profile away from natural and anthropogenic perturbation zone [12]. At the same time, the producer must seek for those practices which will promote sequestration of SOC in croplands without compromising the provision of ecosystem services such as food, fodder, fibre or other agricultural products. Thus, it is very crucial to understand the mechanism of carbon stabilisation by improving the mean residence time (MRT) and by offsetting anthropogenic emissions [13] which is vary according to the climatic condition and soil properties and also on existing soil carbon content of the particular region. For example, the same management practice which are proved to increase SOC can result in high amount of loss and unintended consequences in those soils which are already saturated with organic carbon [14] (**Table 3**).
