**2. Scene of Asian agriculture in GHG emission and carbon storage potential**

According to IPCC (Intergovernmental Panel on Climate Change) 2014 [3] record, the scenario of GHG emission is very critical in Asia as Asian agriculture causes an average of 44% of global agricultural GHG emission (**Table 2**).

The agricultural GHG emission contributors such as enteric fermentation and paddy rice cultivation are the major source of methane emission whereas the major sources of nitrous oxide emission are application of manures and fertilisers. The worldwide contribution of paddy rice cultivation towards GHG emission (CH4) is 11%. For higher crop production farmers rely on synthetic fertiliser application which is a rapidly growing source of emission having the increase rate of around 37% since 2001 [5]. Along with that the use of large number of machineries are the source of CO2 emission due to burning of fossil fuel. The imbalanced fertilisation is another reason for the release of soil carbon to the atmosphere (**Figure 1**).

To meet the daily food requirements, the agricultural stakeholders must make two kind of assessments in order to understand the impact of climate change on food and crop production i.e., mitigation and adaptation. Mitigation will reduce the emission of GHG from agricultural sources whereas adaptation will enable the agricultural sectors to perform well in the existing climate change situation through modified management and production systems. Both the approaches can be regulated through various policies e.g., ensuring the economic value of carbon and its sequestration will be an important development in the agriculture sector [7]. The adaptive-mitigation techniques to capture carbon in soil in organic form is a potential factor for controlling CO2 emission as well as a factor for improving soil quality and health.


**Table 2.**

*Carbon pool size and changes due to human activities [4].*

#### **Figure 1.**

*Contribution of various agricultural sectors towards GHG emission in Asia. See [6].*

Carbon storage in terrestrial system is important as soil can hold three times more carbon than vegetations that they support. The Soil carbon pool which is the largest reactive carbon in terrestrial ecosystem [8], is estimated to be 2500 Pg (1015) up to 1 mt depth, of which soil organic carbon is about 1500 Pg. This stock accounts for about 3.2 times the size of atmospheric carbon pool and 4 times that of biotic pool [6, 9]. Thus, capturing the carbon from agricultural lands in stable form can reduce CO2 content of the atmosphere.

Again, the global distribution of carbon and its storage potential is highly influenced by climatic conditions such as temperature and precipitation [10]. The higher decomposition rate controlled by higher oxidation of organic matter result in lower Soil Organic Carbon (SOC) in the tropics as compared to higher SOC of cooler regions. Though all the parts of Asian croplands contain moderate amount of carbon, and all together they account for about 25% of global cropland carbon [11]. But the regions of South Asia with low level of SOC and with serious degradation problems are global highest in carbon storage per hectare basis (0.62–1.28 t C/ha/ yr) over 2.9 million km2 of land which all together turns out to be 2.2 to 4.5 Pg C storage/yr. in South Asia [11]. Thus, the management practices which are proved to be potential drivers of SOC enrichment must be encouraged as mitigative measure in agricultural soils.
