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Nitrous oxides hit all the wrong environmental buttons

1. Major greenhouse gas emitter

a. Manufacturing and transport of fertiliser are estimated at 6.7 tonnes CO2e tonne of Nitrogen fertiliser. Thus if 850,000 tonnes used, this = 5.7mt CO2e. Out of a total UK GHGs of about 180 mtonnes this = about 3%.

b Add to this the nitrous emissions following fertilser application. In the UK, NOx are 6 per cent. of UK greenhouse gas emissions (parliamentary answer). Agriculture contributes 2/3 of this - ie 4%.

A Life Cycle Analysis (DEFRA funded) into the environmental burdens and resource use in the production of agricultural and horticultural commodities shows that Nitrous oxide (N2O) is the single largest contributor to global warming potential (GWP) for all commodities except tomatoes. Summary of findings

Worldwide fertilisers are the largest source of GHG emissions in agriculture (38% - Meat 31% according to Stern Report Agriculture ) and the single largest source of nitrous oxide emissions in the world.

So N fertilisers are responsible for 3 +  4 = 7% of all UK GHG emissions - more than for all aircraft (a mere 10mt - see total UK GHGs )

Livestock accounts for about 65% of human made nitrous oxides according to LEAD.

Nitrous oxide is a major contributor to climate change (4-6% in UK) - and about 300X more potent than carbon dioxide.

2. Uses masses of oil.

The manufacture of Nitrogen fertiliser is the single main cause of energy use in non-organic farming, accounting for 37% of the total. More from Soil Association.

3. Reducing biodiversity

4. Making ozone at ground level,

5. Reducing ozone in stratosphere and

6 Causing eutrophication of water

No probs there then!

INFORMATION

The natural nitrogen cycle (More about all 'Cycles) has been totally overun by a torrent of "reactive" nitrogen (glossary link). Largely overlooked, the amount of "reactive" nitrogen in the air has risen considerable in last 50 years so much so that farmers in UK now get more reactive nitrogen from the air (particulates and acid rain) than they used to put on their land in 1950s. Once pesticide were "bad" and fertilsers "good". Now it may be the other way round.

More from Wikipedia. See New Scientist graphic for changes.

PLAN/LINKS

3rd Internal Nitrogen Conference addresses the challenge is how to minimize reactive N creation while also maximizing food and energy production.

UNEP Reactive Nitrogen in the Environment

IPCC "Nitrous Oxide Emissions from Agriculture"

To Do: Investigate the question raised at IPC Seminar: 

"Did the IPCC take full account of reactive nitrogen - or did they underestimate its affect in climate change?"

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