Major agricultural source of nitrous oxide (N₂O) is:

Correct option is A

· N₂O forms during nitrification + denitrification of added nitrogen fertilizers.
· IPCC: Fertilizer N contributes ~60% of global agri N₂O.
Why other options are wrong
· (b) Irrigation alone does not create N₂O.
· (c) Pesticides do not emit N₂O.
· (d) Machinery emits CO₂, not N₂O.