Climate change: fertilser versus cars

Over on Frogblog, the Frog argues that fertiliser is worse than cars. Nitrous Oxide (N₂O) emissions are 12.7 MTCO₂-e a year, while transport emissions are only 12.6 MTCO₂-e. The conclusion?

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.

The problem is that not all of those 12.7 MTCO₂-e are from fertiliser. According to the 2007 National Inventory Report, only 1.76 MTCO₂-e was due to "direct emissions from agricultural soils" (which means synthetic fertilisers, as well as use of manure). 7.56 MTCO₂-e was from "animal production" - a polite euphemism for cowpiss - and the remaining 3.38 MTCO₂-e was indirect emissions from runoff. The latter includes some nitrogen from fertiliser, as well as some from animal waste, but without the full worksheets, it's unclear how much of each. But even assuming its all due to fertiliser (and its not), that sets an upper limit on fertiliser emissions of 5.14 MTCO₂-e - less than half of transport emissions.

What this tells us is that going organic is not quite the miracle Frog claims, as organic cows presumably still piss and shit. It's also worth noting that using animal manure as natural fertiliser still counts towards emissions; it doesn't cease to be bad simply because its "natural" (a term we should be careful about applying to agriculture anyway; there's nothing natural about a paddock full of cows being milked every morning).

That said, reducing nitrous oxide emissions is perhaps the cheapest and easiest thing we can do to fight climate change. And as the Sustainability Council pointed out last year, we already have cost-effective ways of doing so. Nitrification inhibitors inhibit the breakdown of fertiliser (and cowpiss) in the soil, while changes in farm management practices can reduce the soil impacts and runoff in the first place. Using these could reduce emissions by 3.7 MTCO₂-e a year - and all while increasing farmers' profits. The problem is overcoming that institutional inertia and the give-a-shit factor and getting them to start doing it. And unfortunately, by refusing to price agricultural emissions until 2013, without any interim policy such as a nitrogen tax or regulation, the government is moving in exactly the wrong direction.