Impact of nitrogen additions on greenhouse gases emissions

Global warming is a real threat to the Earth’s climate system, mainly owing to the rise in atmospheric greenhouse gases (GHGs) concentrations. Agricultural practices including tillage, over fertilization and residue burning are leading source of carbon dioxide (CO2) which is the major GHG in the atmosphere.

The impact of N addition at different stages of plant residue decomposition and residue type on CO2 emissions and soil health parameters was evaluated. A laboratory incubation experiment was carried out in incubation jars along with two different quality residues i.e. wheat and rice residues (10 g residues kg-1 of soil) and one control without residues was also maintained. Nitrogen (132 mg kg-1 of soil) was added at two stages of residue decomposition i.e. (1) at the time of residue addition and (2) after 15 days of residue decomposition.

Our results showed that with addition of crop residues (wheat and rice) there was significant increase in cumulative C-CO2 as well as microbial biomass. Similarly, enzyme activities also enhanced with the addition of crop residues but there was significant decrease in chitinase activity with the addition of wheat residues. While, rice residues significantly enhanced all enzymes activity except acid phosphatase, where there was no significant change. Addition of N at different interval of decomposition has no significant impact on cumulative C-CO2, while microbial biomass decreased in N addition at start and no significant impact by N addition in partially decomposed residues.