Soil organic carbon

Soil organic carbon

Subject :Environment

Section : Climate change

Context: Soil Organic Carbon (SOC) as an indicator for land and soil degradation, is becoming central to climate change mitigation attempts.

More on the News:

• The UN climate conference of 2022 also witnessed calls for integrating soil health and specifically soil organic carbon (SOC) in the Nationally Determined Contributions (NDCs).
• This gains significance, in the background that several IPCC reports have demonstrated the potential of land-based mitigations in the NDCs under the Paris Agreement.
• SOC pool is one of the most important carbon stocks on the earth which contains approximately twice as much carbon as in the atmosphere.
• SOC stock is also proposed as a globally relevant indicator within the monitoring framework for land and soil degradation in the UN Sustainable Development Goals (SDGs).
• SOC management on croplands and grasslands are estimated to have the greatest mitigation potential at USD20 tCO2-eq-1
• India with 162 million hectares (Mha) of arable land and 8 Mha of permanent crop land which is about 12% and 6% of the respective global figures, has a huge potential for integrating SOC in its national mitigation strategies.
• In this context, it is important to investigate the relevance of making SOC, as a central indicator in soil health measurements.
• Soil microbial load is a relatively stable measure of soil health. Soil microbe species diversity and activity are responsible for various ecosystem services. The higher the microbial load in the soil, higher is the aerobic activity and better the soil health and SOC.

Soil Organic Carbon

• Soil organic carbon (SOC) comes from plants, animals, microbes, leaves and wood, mostly found in the first metre or so.
• Soil organic carbon is a measureable component of soil organic matter. Organic matter makes up just 2–10% of most soil’s mass and has an important role in the physical, chemical and biological function of agricultural soils.
• Organic matter contributes to nutrient retention and turnover, soil structure, moisture retention and availability, degradation of pollutants, and carbon sequestration.
• Soil organic matter is composed mainly of carbon, hydrogen and oxygen, and has small amounts of other elements, such as nitrogen, phosphorous, sulfur, potassium, calcium and magnesium contained in organic residues.
• It is divided into ‘living’ and ‘dead’ components and can range from very recent inputs, such as stubble, to largely decayed materials that might be many hundreds of years old. About 10% of below-ground SOM, such as roots, fauna and microorganisms, is ‘living’.