Recommended
More Related Content
What's hot
What's hot (20)
Similar to Soil carbon saturation
Similar to Soil carbon saturation (20)
Recently uploaded
Recently uploaded (20)
Soil carbon saturation
- 1. Rishabh Srivastava ES-21460 INDIAN AGRICULTURAL RESEARCH INSTITUTE Seminar in-charge Dr. Sandeep Kumar Scientist (Environmental Scien Division of Environment Scien
- 2. • Soil organic carbon (SOC) is one part in the much larger global carbon cycle that involves the cycling of carbon through the soil, vegetation, ocean and the atmosphere . • The SOC pool stores an estimated 1500 PgC in the first meter of soil, which is more carbon than is contained in the atmosphere (roughly 800 PgC) and terrestrial vegetation (500 PgC) combined (FAO and ITPS, 2015) • This phenomenal SOC reservoir is not static, but is constantly cycling between the different global carbon pools in various molecular forms (Kane, 2015). INDIAN AGRICULTURAL RESEARCH INSTITUTE What is SOC ?
- 6. Global carbon cycle •Organic material transformation process results in a complex biogeochemical mixture of plant litter compounds and microbial decomposition products in various stages of decomposition. (Von Lützow et al., 2006; Paul, 2014) INDIAN AGRICULTURAL RESEARCH INSTITUTE
- 7. INDIAN AGRICULTURAL RESEARCH INSTITUTE INDIAN AGRICULTURAL RESEARCH INSTITUTE Top Soil 1500Pg of SOC 900-1700Pg of inorganic carbon Atmospehere 750 Pg C (Eswaran et al. 1993; Schlesinger 1997). 60 PgC yr-1
- 9. SOIL CARBON SATURATION The concept of soil carbon saturation implies that the soil carbon stock has reached its maximum carrying capacity for storing soil carbon inputs (Six et al., 2002; Stewart et al., 2007). This threshold, which depends on many factors including inherent and dynamic soil properties and their interactions with abiotic factors, is also referred to in literature as the maximum carbon stabilization capacity (Beare et al., 2014). Soils that are depleted of SOC have the greatest potential to gain carbon, but also have the least propensity to do so. Since the majority of soils around the world are far from their saturation thresholds, there is great potential for increased carbon inputs and management that protects existing stocks to maximize soil carbon sequestration(Kane, 2015). INDIAN AGRICULTURAL RESEARCH INSTITUTE INDIAN AGRICULTURAL RESEARCH INSTITUTE
- 10. SOC is divided into different pools as a function of its physical and chemical stability Pool Turnover Period Fast pool (labile/active pool) 1–2 years. Intermediate pool 10-100 years Slow pool (refractory/stable pool) 100 to >1 000 years Pyrogenic SOC : formed from partially carbonized (e.g., pyrolyzed) biomass during wildfires which is present in many ecosystems (Schmidt and Noack, 2000) (FAO and ITPS, 2015; O’Rourke et al., 2015):
- 12. Soil organic matter SOM contains roughly 55–60 percent C by mass. In many soils, this C comprises most or all of the C stock – referred to as SOC – except where inorganic forms of soil C occur (FAO and ITPS, 2015). The protection of OM against decomposition by the described mechanisms decreases in the order: chemically protected > physically protected > biochemically protected > non-protected (Kogel-Knabner et al. (2008), SOM can be divided into different pools Active pools - turnover in months or few years; Passive pools - turnover in up to thousands of years.
- 13. Assessment of C in the soil
- 14. Limiting Factors for C storage
- 15. Meena et al., 2017
- 16. Stabilization of C in soil The three mechanisms depend on a number of biotic, abiotic and management factors that shape their soil carbon stabilization efficacy. (Six et al., 2006; Kane, 2015).
- 19. Zonal model Kleber et al., 2007
- 20. Micro aggregate model Lehmann et al., 2007
- 21. Conclusion……….. The shear size of the soil carbon pool and the annual flux of carbon passing through the soil are two of the reasons that SOC can play a significant role in mitigating GHG emissions. Currently, there is not enough research on the topic of anthropogenic impacts on the formation and loss of soil inorganic C to be able to assess its sequestration potential and it is only the organic C pool that is under consideration for inclusion in various emission reduction schemes. INDIAN AGRICULTURAL RESEARCH INSTITUTE INDIAN AGRICULTURAL RESEARCH INSTITUTE
- 22. INDIAN AGRICULTURAL RESEARCH INSTITUTE CASE STUDY - 1 INDIAN AGRICULTURAL RESEARCH INSTITUTE Objective: Soil carbon saturation: concept, evidence and evaluation
- 23. Introduction Most current SOC models employ first-order kinetics for decomposition processes, and therefore the models predict linearity between C input level and SOC level at equilibrium (i.e., steady-state; Paustian et al. 1997) Many long-term agroecosystem field experiments, in which treatments give different levels of C inputs, show soil C stocks that appear linearly related to the average amount of C returned to the system (e.g. Huggins et al. 1998b; Kong et al. 2005; Paustian et al. 1997a). Saturation limits to individual SOC pools have been proposed by other researchers, due to silt + clay protection (Hassink 1996, 1997), soil structure (physical protection within aggregates), and the biochemical complexity of the organic compounds (Baldock and Skjemstad 2000). INDIAN AGRICULTURAL RESEARCH INSTITUTE INDIAN AGRICULTURAL RESEARCH INSTITUTE
- 24. Linear model •Proposed by Jenny (1941) and other early workers) •The simple first-order decay model •assumes that the amount of C entering a C pool is independent of the pool size •decomposition rates are directly proportional to the size of the pool
- 25. Carbon saturation model Hassink and Whitmore, 1997 •The C saturation model has a whole soil saturation limit (Cm) due to inherent physicochemical limitations. •The fundamental relationship between C addition levels and soil C levels at steady-state is asymptotic. •expressed as a simple modification to the C input term
- 26. Mixed model •where, k1 and k2 is decomposition constant •a is partitioning coefficient for losses from C1, and transfer of decomposition products to the more stable pool C2 Stewart et al., 2007
- 27. Contd….. As C2 approaches saturation, the amount of decomposed products from C1 transferred into C2 decreases and ceased at saturation point. At this point SOC accumulation in C1 proceeds according to the linear model
- 32. Conclusions Soils that show 1. no increase in SOC stock with increasing C input levels 2. high C content soils having decreased C stabilization efficiency suggest an upper limit, or saturation limit to whole soil C.
- 33. Objective: Carbon saturation in the silt and clay particles in soils with contrasting mineralogy CASE STUDY - 2 INDIAN AGRICULTURAL RESEARCH INSTITUTE INDIAN AGRICULTURAL RESEARCH INSTITUTE
- 34. Introduction The goal of this study was to elucidate whether or not the silt and clay fractions are saturated in temperate and subtropical soil from Chile and Mexico, respectively. C-saturation depends on the potential of silt and clay fractions to stabilize soil organic matter (SOM) from microbial mineralization (Baldock and Skjemstad, 2000) The C pool of a soil fraction displaying linear accumulation is interpreted as not being influenced by C saturation, while the opposite is true for a C pool exhibiting a plateau or asymptotic influence (Diekow et al., 2005; Stewart et al., 2008). INDIAN AGRICULTURAL RESEARCH INSTITUTE INDIAN AGRICULTURAL RESEARCH INSTITUTE
- 35. Materials & Method Sampling Sites Soil Sampling Physical Fractionation Carbon Analysis Statistical Analysis
- 38. Discussion As expected, C in 2:1 soils was higher than that in 1:1 soil, indicating that the nature of clay type plays an important role in SOC accumulation (Feller and Beare, 1997) Vertisols dominated by smectitic mineral clay have been reported to contain greater amounts of organic matter than soils dominated by kaolinite, feldspars and quartz (Ngole and Ekosse, 2009) However, subtropical Ferrasols, having a mixed clay type, showed higher SOM than temperate soils. This result reflects influence of management practices involving hand tilling and occasional plowing by animal traction with decades of maize and beans cultivation, leading to greater amount of C in
- 40. Conclusions The results of the present study confirm early findings that individual particles such as clay fraction can achieve a maximum C accumulation or saturation. When this maximum is reached, further inputs of new organic matter cannot be physically protected in the clay fraction and organic compounds progressively accumulate in the silt fraction and as uncomplexed free materials, namely particulate (POM) or free organic matter in the sand-sized fraction (Matus et al., 2008).
- 41. Contd…… On average, the clay fraction of temperate soils was saturated at 1.9±0.1 g C kg-1 in 2:1 soils and 1.0±0.1g C kg-1 in 1:1 soils, while in subtropical soils they were saturated at 13.6±0.7 g C kg-1. C accumulation in the silt fraction was explained in terms of partial reactivity and habitat pore space for microbial growth. Thus, the silt fraction allows linear C accumulation in similar proportions across SOC levels. the low C in < 2 μm fraction in temperate soils having 2:1 clay compared to subtropical Ferrasols (mixed clay) can be explained by the stabilization of C within the micro- aggregates (Caner et al., 2010).
- 42. I can fight Climate change - SOC INDIAN AGRICULTURAL RESEARCH INSTITUTE
Editor's Notes
- Soil organic carbon sequestration is the process by which carbon is fixed from the atmosphere via plants or organic residues and stored in the soil.
- It infers that soil carbon stabilization curves are not infinitely increasing, and that when a C saturation level is reached, SOC sequestration comes to an end, soils stop being a net carbon sink and may become a net carbon source. As such, SOC sequestration has spatial and temporal limitations and is a reversible process (Paustian et al., 2016).
- C stabilization efficiency decreased in soils with high SOC content.