Soils play an important role in the global carbon cycle. Agricultural lands in semi-arid and arid regions occupy a substantial portion of the world¿s cultivated fields. The potential contribution of these lands towards the global carbon cycle should not be ignored. Soil carbon pool can be divided into the organic and the inorganic carbon forms. With regard to the former, cultivation of soils is known to generate a significant reduction in soil organic carbon (SOC) content.In addition, in semi-arid and arid regions, organic carbon content is a priori low and the climatic conditions are unfavourable for its accumulation in cultivated lands. Carbon sequestration in inorganic forms may prove to be a viable alternative, especially in semi-arid and arid regions, where soil inorganic carbon (SIC) is an important component of the carbon pool. Evaluating SIC sequestration is complicated because of the uncertainty regarding the definition of SIC sequestration. Some consider accumulation of solid carbonate as SIC sequestration, while others consider dissolution of solid carbonate as SIC sequestration. Soils and sub-soils from semi-arid and arid regions commonly contain calcium carbonate (CaCO3). Under cycles of soil wetting and drying, the CaCO3 is subject to dissolution and re-precipitation. Thus, evaluation of SIC sequestration requires monitoring of the changes in the inorganic forms of C in the gas, liquid and solid phases.The overall objective of the proposed study is to develop agricultural management strategies for increasing carbon sequestration (in both organic and inorganic forms) in soils from semi-arid and arid region. This goal will be attained by integrating the results from detailed field measurements and laboratory studies to evaluate the effects of soil properties, tillage intensity and organic matter load on the carbon sequestration in irrigated and rain fed cultivated arid and semi-arid lands.