I spent most of yesterday at a symposium organised by the Australian Institute of Agricultural Science and Technology. A lot of topics were discussed, but one that interested me was methane, mainly that emitted from both ends of ruminants such as cows.
There’s plenty to to say about this, but I’m just going to repeat one point that I made briefly and that subsequent speakers like Snow Barlow from Melbourne expanded on. Methane belched or farted by a cow is not just a greenhouse gas, it’s nutrition wasted by the digestive process. So, if we can find ways to reduce methane emissions, they should also increase the productivity of agriculture.
That’s not to say that there are $50 bills lying in every cowpat, waiting to be picked up. If there were a cheap and easy way of improving digestion it would have been found by now. But there’s certainly a potential for increased output to offset the costs of finding, developing and implementing ways of reducing methane emissions, for example by making cows fart like kangaroos
As an illustration of the complexities, some other research reported at the symposium showed that having more CO2 in the atmosphere will increase the growth of some tropical grasses (this was a bit of a surprise because these are C4 plants, generally thought to benefit less from this effect), but will reduce the nutrient quality which makes digestion more difficult and therefore tends to increase methane emissions. For any “Greening Earth’ fans out there, I should point out that, as in previous work, studies reported at the symposium found that adverse effects of higher temperatures and more variable rainfall will outweigh any net benefits of CO2 fertilisation