Carbon sequestration (CS) has been increasingly viewed as one of the crucial issues/strategies to address the challenging issues of global warming led climate change effects besides imparting sustainability to productivity. In agricultural land use systems, increased CO2 emission into the atmosphere is through repeated and frequent cultivation of croplands, crop residues, biomass burning, shifting cultivation, cultivation of low biomass producing crop cultivars, land degradation, deforestation, etc. The results of current review revealed that agricultural soils have lost about 30–75% of their inherent soil organic carbon (SOC) pool which is quite alarming. The U.N. panel (IPCC) in its current report published that to contain warming at 1.5oC, there will be a need to reduce the global net CO2 emissions (manmade) by about 45% by the year 2030 from 2010 levels and further to reach ‘net zero’ by 2050. The potential of carbon sequestration with cautious management of world cropland include 0.08±0.12 Pg/yr by erosion control, 0.02±0.03 Pg/yr by preservation of harshly problematic/degraded soils, 0.02±0.04 Pg/yr by repossession of salt-affected soils, 0.15±0.175 Pg/yr by taking up of minimum/conservation tillage and crop left-over administration, 0.18±0.24 Pg/yr by execution of better cropping system and 0.30±0.40 Pg/ yr as C balance via biofuel production. The total potential of carbon sequestration by the world cropland is about 0.75±1.0 Pg/yr. Each 1 Mg/ha rise in soil organic carbon pool in the root zone under the soil would enhance yields of crops by 20–70 kg/ha in case of wheat, 10–50 kg/ha in rice, and 30–300 kg/ha in corn, augmenting production of cereals and legumes in the developing countries by 32 and 11 million Mg/yr, respectively. Therefore, CS apart from mitigating global warming potential also succors the farming community and the nation in advancing food security on sustainable basis.

Activation barriers for geometrical isomerism and tautomerization have been studied for carbamic acid and its mono- and dichalcogenide analogs at B3LYP/6-31+G*, MP2/6-31+G*, and G2MP2 theoretical levels. The studies indicate that carbamic acid with higher chalcogen prefers chalcogen at the chalcogenol position. Proton affinities, gas-phase acidities and atomic charges for these molecules have also been evaluated. Unimolecular, bimolecular, and two-step pathways for the decomposition of carbamic acid and its analogs are also analyzed, from which it was concluded that the two step mechanism is the more plausible pathway.