One of the main reasons for the differences in soil carbon between organic and conventional systems is that synthetic nitrogen fertilizers degrade soil carbon. Research shows a direct link between the application of synthetic nitrogenous fertilizers and decline in soil carbon.
Scientists from the University of Illinois analyzed the results of a 50-year agricultural trial and found that synthetic nitrogen fertilizer resulted in all the carbon residues from the crop disappearing as well as an average loss of around 10,000 kg of carbon per hectare per year. This is around 36,700 kg of CO2 per hectare on top of the many thousands of kilograms of crop residue that is converted into CO2 every year. Researchers found that the higher the application of synthetic nitrogen fertilizer the greater the amount of soil carbon lost as CO2. This is one of the major reasons why most conventional agricultural systems have a decline in soil carbon while most organic systems increase soil carbon. Essentially, soils lost their ” Stable” humic because of conventional agricultural practices. Which negatively impacted soils physical, chemical & biological functionalities.