Soil organic carbon is the basis of sustainable agriculture. Farmers are interested in retaining and increasing soil organic carbon for individual fields in order to improve soil health and yield. One of the main reasons behind this is the ability of soil organic carbon in maintaining the soil fertility. SOC improves soil aeration, water retention capacity, drainage, and enhances microbial growth. As carbon stored in the soil is increased carbon is “sequestered” (long -term storage) and risk of loss of nutrients through leaching and erosion is reduced. When the amount of carbon in the soil is increased it reduces the amount of carbon dioxide present in the atmosphere which provides a better climatic condition for plant growth. An increase in soil organic carbon results in more stable carbon cycle and enhanced overall agricultural productivity.
Unsustainable management practices like excessive irrigation, over grazing, deforestation, excessive tillage, practice of burning agricultural fields also causes soc losses. A large amount of carbon in the soil is reduced due to plant harvesting processes. The process of decomposition done by micro-organisms present in the soil where half of the organic carbon is released in the form of carbon dioxide is a major reason behind soil organic carbon depletion. Greater root bio-mass also results in carbon loss due to increased rate of respiration that take place through these roots. The amount of organic carbon present in the soil is affected by factors like climate, texture, hydrology (water content), land use and vegetation. When the amount of carbon in soil is reduced it affects the ability of soil to supply nutrients to the plant which in turn leads to low yield and affect food security. It also reduces the soil bio-diversity since it affects the growth of microbes. Global warming also contributes in depletion of organic matter present in the soil.
Soil carbon storage is a vital ecosystem service. In an agricultural land soil carbon loss takes place as a result of improper methods of soil managements such as excessive tillage, increased rate of irrigation, increased use of chemical fertilizers etc.