Context:
Global Nitrous Oxide Assessment has recently been published by the United Nations Environment Programme & the Food and Agriculture Organization.
Key Findings of the report:
- Global Warming Impact – N₂O currently contributes 0.1°C to global warming.
- Anthropogenic Emissions increased by 40% since 1980, with 75% originating from agriculture (synthetic fertilizers and manure).
- Ozone Depletion – N₂O is the leading ozone-depleting substance, increasing harmful UV exposure.
- Emissions Sources –
- Agriculture – 75% of emissions, with 90% from synthetic fertilizers and manure on soils, and 10% from manure management.
- Industry – Accounts for 5% of emissions.
- Others – Fossil fuel combustion, wastewater treatment, aquaculture, biomass burning, etc.
Nitrous Oxide (N₂O):
- A greenhouse gas 300 times more potent than CO₂.
- 3rd highest concentration among GHGs responsible for global warming.
- Can live in the atmosphere for up to 120-125 years.
- Absorbent sinks of Nitrous Oxide –
- Soils – Microbial processes consume and reduce N₂O emissions. Denitrifying bacteria convert N₂O to nitrogen gas (N₂) under anaerobic conditions.
- Oceans – Deeper and subsurface oceans absorb N₂O from the atmosphere. Besides, marine phytoplankton play a role in consuming dissolved N₂O.
- Stratosphere – N₂O reacts with ozone (O₃), leading to the formation of nitrogen oxides (NOx) and ultimately nitrogen gas (N₂).
- Mitigation measures –
- Use enhanced-efficiency fertilizers and slow-release formulations.
- Transition to renewable resources in transportation and energy production.
- Balance nutrient inputs in animal feed, reduce grazing intensity, and apply anaerobic digestion of manure.
- Adopt targets like the Gothenburg Protocol (1999 protocol that sets limits on air pollutants including sulfur dioxide, nitrogen oxide, ammonia and volatile organic compounds)
Source: Down to Earth
Previous Year Question
Why does the Govt promote the use of Neem-coated Urea’ in agriculture?
[UPSC Civil Service Exam – 2016 Prelims]
(a) Release of Neem oil in the soil increases nitrogen fixation by the soil microorganisms.
(b) Neem coating slows down the rate of dissolution of urea in the soil.
(c) Nitrous oxide, a greenhouse gas, is not at all released into atmosphere by crop fields.
(d) It is a combination of a weedicide and a fertilizer for particular crops
Answer: (b)