Soil Organic Carbon

  • Soil organic carbon plays a key role in maintaining soil fertility by holding nitrogen, phosphorous and a range of other nutrients for plant growth.
  • Holding soil particles together as stable aggregates improving soil properties such as water-holding capacity and providing gaseous exchange and root growth playing an important role as food source for soil fauna and flora and even suppressing crop diseases and acting as a buffer against toxic and harmful substances such as absorption of toxins and heavy metals.
  • Soil Organic Carbon improves soil aeration (oxygen in the soil) and water drainage and retention and reduces the risk of erosion and nutrient leaching.
  • Soil Organic Carbon is also important to chemical composition and biological productivity including fertility and nutrient holding capacity of a field.
  • As carbon stores in the soil increase, carbon is “sequestered” and the risk of loss of other nutrients through erosion and leaching is reduced.
  • An increase in Soil Organic Carbon typically results in a more stable carbon cycle and enhanced overall agricultural productivity.
  • While physical disturbances of the soil can lead to a net loss of carbon into the surrounding environment due to formation of carbon dioxide.
  • Conventional practices followed by farmers such as leaving the land fallow for some time to allow it to regain its lost nutrition and appropriate crop rotation have been junked in favor of continuous cropping which has led to a decline in Soil Organic Carbon (SOC) content to 0.3-0.4 per cent in the country when it should ideally be at 1 to 1.5 per cent.
  • Organic matter plays a key role in maintaining soil fertility by holding nitrogen and sulphur in organic forms and other essential nutrients such as potassium and calcium. The loss of organic matter is accelerated by frequent tillage.

      

Management practices

 

           Functions and explanation

 Conservation tillage practices    
Conservation tillage practices including no-till management aid
in storing soil organic carbon, keeping the physical stability of the soil
intact. When reduced-till systems are combined with residue management and
manure management, soil organic carbon can increase over time.
 Crop residue management Returning crop residue to the soil adds carbon and helps to
maintain soil organic matter.
 Cover crops Cover crops can increase soil carbon pools by adding both root
and above ground biomass. Covers also reduce the risk of soil erosion and the
resulting loss of carbon with soil particles. Cover crops also enhance
nutrient cycling and increase soil health over time.
 Manure and compost Adding organic amendments such as manure or compost can directly
increase soil carbon, and also result in increased soil aggregate stability.
This enhances the biological buffering capacity of the soil, resulting in
greater yields and yield stability over time.
 Crop selection Perennial crops eliminate the need for yearly planting and
increase soil organic carbon by root and litter decomposition post-harvest.
Crops with greater root mass in general add to root decomposition and
physically bond aggregates together. Using high residue annual crops can also
help reduce net carbon loss from cropping systems.