Futures Forum: Climate change: and nitrous oxide

Thursday, 23 July 2015

Climate change: and nitrous oxide

The use of nitrogen is big in farming:
Futures Forum: Norman Borlaug and the “Green Revolution”: a centenary

Maybe it should be less:
Futures Forum: Climate change: and farming with less nitrogen

It's very much in the news:
Pacific Nitrous Oxide Emissions More Than Thought

This is the latest from the Arthur Rank Centre:

Nitrous Oxide is over 300 times more harmful than carbon dioxide and about 66% of man-made Nitrous Oxide emissions come from agriculture.
It’s an important greenhouse gas because it’s very efficient at absorbing energy and it stays in the atmosphere for a long time.
Natural emissions of N2O can be increased by a variety of agricultural practices and activities, including the use of synthetic and organic fertilisers, production of nitrogen-fixing crops, cultivation of high organic content soils, and the application of livestock manures and slurries to growing crops.

Nitrous oxide - RuSource
RuSource

And this is the latest from the Farm Carbon Cutting Toolkit:

16.07.15 Theme of the month: Nitrous Oxide

So we are having a bit of a change this month and focussing for the next few weeks on nitrous oxide and the issues that arise from agriculture and land use that concern emissions.

The deal with Nitrous Oxide

Nitrous Oxide is over 300 times more harmful than carbon dioxide, so reducing the emissions of this gas is particularly important.

About 66% of man made nitrous oxide emissions come from agriculture. Within agriculture, nitrous oxide is emitted from the nitrogen in fertiliser, manure and slurries, and crop residues. The next most important sources are burning fossil fuels for energy and transport, making up 15% of emissions and forest fires and biomass cooking at 11%.

Warming impact

Although there is a far lower concentration of nitrous oxide in the atmosphere than carbon dioxide, it’s a important greenhouse gas for two reasons, its very efficient at absorbing energy and it stays in the atmosphere for a long time.

Agricultural sources of nitrous oxide

Nitrous Oxide (N₂O) is produced naturally in soils through the microbial processes of denitrification. These natural emissions of N₂O can be increased by a variety of agricultural practices and activities, including the use of synthetic and organic fertilisers, production of nitrogen-fixing crops, cultivation of high organic content soils, and the application of livestock manures and slurries to growing crops. All of these practices directly add additional nitrogen to soils, which can then be converted to N₂O. Indirect additions of nitrogen to soils can also result in N₂O emissions. Surface run-off and leaching of applied nitrogen into ground water and surface waters can also result in indirect additions of nitrogen to the soil. Nitrous oxide is also produced through the denitrification of the organic nitrogen in livestock manure and urine. The production of N₂O from livestock manure is likely to depend on the composition of the manure and urine, the type of bacteria involved in the process, and the amount of oxygen and liquid in the manure system.

What can we do about it?

We can’t get away from the fact that nitrous oxide naturally occurs as part of the nitrogen cycle. However we can influence the amount of indirect emission by adapting the way that we manage our soils, manures, fertilisers and rotations. These are the things that we will be focussing on this month (and hopefully provide you with lots of useful insights for you to consider whilst sitting on your tractor for harvest!).

Sources: FCCT Toolkit, IPCC report, Davidson and Kanter, (2014) Inventories and scenarios of nitrous oxide; Environmental Research Letters

16.07.15 Theme of the month: Nitrous Oxide
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