Carbon sequestration is the long term storage of carbon in oceans, soils, vegetation (especially forests), and geologic formations. Although oceans store most of the Earth?s carbon, soils contain approximately 75% of the carbon pool on land three times more than the amount stored in living plants and animals. Therefore soils play a major role in maintaining a balanced global carbon cycle. Through the process of photosynthesis, plants assimilate carbon and return some of it to the atmosphere through respiration. The carbon that remains as plant tissue is then consumed by animals or added to the soil as litter when plants die and decompose. The primary way that carbon is stored in the soil is as soil organic matter (SOM). SOM is a complex mixture of carbon compounds, consisting of decomposing plant and animal tissue, microbes (protozoa, nematodes, fungi, and bacteria), and carbon associated with soil minerals. Carbon can remain stored in soils for millennia, or be quickly released back into the atmosphere. Climatic conditions, natural vegetation, soil texture, and drainage all affect the amount and length of time carbon is stored.

Removing CO2 from the atmosphere is only one significant benefit of enhanced carbon storage in soils. Improved soil and water quality, decreased nutrient loss, reduced soil erosion, increased water conservation, and greater crop production may result from increasing the amount of carbon stored in agricultural soils. One of agriculture?s major opportunities to help mitigate the effects of climate-warming gases lies in management of soil to increase organic content, thereby removing carbon from the atmosphere.  Maintaining and increasing soil organic matter (SOM) adds to soil fertility, water relation, and crop production. Many scientists are conducting studies to determine which agricultural practices will in fact sequester carbon. Recent studies demonstrate that a number of biological, soil-based practices employed in integrated systems have great potential to sequester carbon. Recently many soil scientists have suggested that the sequestration of atmospheric carbon dioxide in SOM could also contribute significantly to attempts to the Kyoto Protocol. Conversion of large areas of cropland to conservation tillage, including no-till practices, during the next 30 years could sequester all the CO2 emitted from agricultural activities.

The most promising systems for carbon sequestration in soil combine crop rotation and low or no inputs of pesticides, herbicides, and industrial fertilizers. Long-term studies suggest that such systems build significant quantities of soil organic carbon through a variety of mechanisms such as enhanced abundance of mycorrhizal fungi. Management techniques, which are successful in providing a net carbon sink in soils, include Conservation tillage, cover cropping, crop rotation, minimum tillage, etc. Through all these practices there will be significant increase in the level of soil organic matter which binds the carbon dioxide within the soil and helps to reduce its level in the atmosphere. There is still much to learn about carbon sequestration in the soil. Many researches has been currently ongoing to address issues that include the impacts of land use and land management on soil carbon sequestration and ways to increase the storage time of carbon in the soil, the underlying mechanisms controlling soil structure and the storage of carbon  these include various chemical, physical, biological, mineralogical, and ecological processes and the relationships between biodiversity, atmospheric CO2 levels, and increased nitrogen deposition in carbon storage.