Fertilizer worse than cars

by frog

It’s now fairly well known that about half of New Zealand’s carbon emissions come from our agricultural sector. Many who don’t want to face up to climate change use this as a convenient excuse: ‘well, you can’t really stop cows burping, it’s all natural, it’s not a problem that we need worry about’.Even were that true, according to the 2007 Environment Report about a third of those agricultural emissions are caused by:

nitrous oxide emissions… associated with the application of fertilizers, animal effluent deposited on agricultural soils and the use of nitrogen fixing crops.

These nitrous oxide emissions rose 27% between 1990, when New Zealand signed Kyoto, and 2005. They equate to 12.7 megatonnes of carbon dioxide equivalent compared to all the road transport in New Zealand which equated to 12.6 megatonnes of carbon dioxide equivalent. The vast majority of that nitrogenous fertilizer is made from natural gas.

So something as simple as turning our over-fertilized industrial farms into diverse, low impact, organic farms could have had the same effect as removing nearly all cars from our roads. Not something that needs $700 million worth of research to work out, but worth doing nonetheless.

[ERRATUM]

Oops, it seems I misrepresented the Environment 2007 Report. As idiot/savant points in a comment below:

Sorry to piss on your parade, but you’re attributing all N2O to fertiliser, and that’s just incorrect. According to the 2007 Inventory Report, N2O emissions from agricultural soils were 12.7 MT Co2-equivalent, but only 1.76 MTCO2-e was “direct emissions from agricultural soils?. 7.56 MTCO2-e was from “animal production? (which means shit and piss from cows, sheep etc), and the remainder (3.38 MTCO2-e) was indirect emissions due to leaching and runoff. The nitrogen here is from both sources, fertilser and animals, but if the ratio is preserved,then around 20% of them – ~0.6 MTCO2-e – can be attributed to fertiliser.

What this tells us is that going organic won’t help, because organic cows still shit and piss. However, we do have cheap options to reduce these, in the form of changes in farm management practices and use of nitrification inhibitors (which work on nitrogen from any source). These are already cost-effective, and their use could reduce emissions by 3.7 MTCO2-e a year. The problem is that farmers won’t use them, because they do not have to pay for their emissions. That may change after 2013, but we need to step on this now, not in five years’ time.

Which means that all the stuff I said about comparisons to transport and organics does not hold water. Thanks I/S. I’ve said before that you keep the partisan bloggers among us honest.

However, I would still argue that well run healthy, polycultural organic farms are more likely to return nitrates from cow and sheep back into their farm’s life-cycle than large, monocultural, industrial dairy farms for instance. Which means massively less carbon equivalent emissions.

frog says

Published in Environment & Resource Management by frog on Wed, March 12th, 2008   

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