@ Eetela, it is the most difficult exercise to enrich the organic carbon in the soil. To my experience if you can enrich 10% more of the present status, you are very lucky. The practices for enrichment of organic carbon in the soil are:

Thank u very much sir @ J. C. Tarafdar

Hello!

In Brazil we encourage some techniques such as no-till, recuperation of degraded pastures and crop rotation could increase the C content.

The range depends on your objective.

The use of well decomposed organic manure is the sure way of adding carbon to the soil.

Remember that diffrent manures have different concentrations of organic carbon

Increasing of organic carbon content in soils it may take 10-20 years that is also depends upon the soil internal & external profile characteristics. We can increase the organic carbon by applying manures, bone meal, FYM and vermicompost..