Spatial Pattern of Soil Carbon Density in Cultivated Land of Different Domains of Madhya Pradesh

Present study was conducted in the Department of Soil Science JNKVV, Jabalpur during 2018-2020. GPS based 531 soil samples were collected from each domain viz., Bhopal, Jabalpur, Vidisha and Hoshangabad of 10.1 Agro ecological sub region (AESR). The samples analyzed for soil organic carbon (SOC) and calcium carbonate (CaCO3) then soil organic carbon density (SOCD), total organic carbon density (TOCD), soil inorganic carbon density (SICD) and total carbon density (TCD) in Mg C ha-1 were calculated. The results of SOCD, TOCD, SICD and TCD ranged from 4.73 to 25.12, 9.22 to 48.98, 1.00 to 21.29 and 11.08 to 68.80 Mg C ha-1 with mean value of 12.19, 23.78, 7.58 and 31.36 Mg C ha-1 in AESR 10.1 and Coefficient of variation (CV) 37.58, 37.58, 50.88 and 31.24 %. The overall trend in SOCD was Bhopal > Vidisha > Jabalpur > Hoshanagabad and SICD was Vidisha > Hoshanagabad > Jabalpur >Bhopal while TCD was in trend of Bhopal > Vidisha > Hoshangabad> Jabalpur. Geo-statistical indicated that Ordinary Kriging used and all variogram were in isotropic form. In Bhopal domain, Gaussian model best fitted for of SOCD, TOCD, and TCD but spherical model for SICD. In Jabalpur domain, exponential domain best fitted for TCD and TOCD but for SICD, spherical model and for SOCD, Gaussian model is best fitted. In Vidisha domain, exponential model best fitted for all. In Hoshangabad domain, exponential model is best fitted for SOCD and TOCD and Gaussian and J-Bessel model best fitted for TCD and SIC, respectively. The nugget/ sill (N/S) ratio was <25% which exhibit strong SD only for SICD in Bhopal domain. The N/S ratio was found to be >25% but <75% which showed moderate SD, for SOCD, TOCD and TC, TOCD, SICD and TCD; SOCD, TOCD, SICD and TCD and SOCD, TOCD, SICD and TCD in Bhopal, Jabalpur, Vidisha and Hoshangabad domain, respectively. The correlation range (m) for SOCD, TOCD, SICD and TCD are 5448.413, 4809.535, 360.522, and 5113.050; 7201.044, 6601.044, 611.651, and 8438.711; 5734.559, 7334.398, 1323.773, and 7881.289 and 5418.684, 5433.206, 8887.656, and 1836.274 in Bhopal, Jabalpur, Vidisha and Hoshangabad domain, respectively. The carbon density was found in order of Jabalpur> Hoshangabad >Vidisha > Bhopal.

Blue carbon stock of the seagrass meadows of Gulf of Mannar and Palk Bay off Coromandel Coast, south India

Blue carbon stock of the seagrass meadows of Gulf of Mannar and Palk Bay, off Coromandel Coast, south India, were computed from the organic carbon content and dry bulk densities of sediment core taken from the seagrass meadows of these two ecosystems. The Gulf of Mannar (GoM) and Palk Bay (PB) harbour 13 seagrass species dominated by Cymodocea serrulata and Syringodium isoetifolium. The soil carbon density of both GoM and PB were higher in subsurface cores. The blue carbon stock of seagrass meadows of the GoM was estimated as 0.001782 Tg and that of PB as 0.043996 Tg. The estimated value of blue carbon stored in seagrass meadows of GoM was 17820 US$ and that of PB was 43,99,682 US$. The results of this study are discussed in the light of climate change mitigation, emphasising the need to conserve these underwater meadows.

Potential shift from a carbon sink to a source in Amazonian peatlands under a changing climate

Amazonian peatlands store a large amount of soil organic carbon (SOC), and its fate under a future changing climate is unknown. Here, we use a process-based peatland biogeochemistry model to quantify the carbon accumulation for peatland and nonpeatland ecosystems in the Pastaza-Marañon foreland basin (PMFB) in the Peruvian Amazon from 12,000 y before present to AD 2100. Model simulations indicate that warming accelerates peat SOC loss, while increasing precipitation accelerates peat SOC accumulation at millennial time scales. The uncertain parameters and spatial variation of climate are significant sources of uncertainty to modeled peat carbon accumulation. Under warmer and presumably wetter conditions over the 21st century, SOC accumulation rate in the PMFB slows down to 7.9 (4.3–12.2) g⋅C⋅m−2⋅y−1 from the current rate of 16.1 (9.1–23.7) g⋅C⋅m−2⋅y−1, and the region may turn into a carbon source to the atmosphere at −53.3 (−66.8 to −41.2) g⋅C⋅m−2⋅y−1 (negative indicates source), depending on the level of warming. Peatland ecosystems show a higher vulnerability than nonpeatland ecosystems, as indicated by the ratio of their soil carbon density changes (ranging from 3.9 to 5.8). This is primarily due to larger peatlands carbon stocks and more dramatic responses of their aerobic and anaerobic decompositions in comparison with nonpeatland ecosystems under future climate conditions. Peatland and nonpeatland soils in the PMFB may lose up to 0.4 (0.32–0.52) Pg⋅C by AD 2100 with the largest loss from palm swamp. The carbon-dense Amazonian peatland may switch from a current carbon sink into a source in the 21st century.