I like cows. I enjoy a nice piece of steak every so often, consider cheese not only a separate food group but a necessity for life and think cream is floaty. I’m also thankful for some of the manure that graces my compost pile, invigorating my soil microbes. But what the hell is this country going to do with the effluent produced by 4.4 million dairy cows?
I was thinking how gross that was when it suddenly struck me, “Hold up a minute, that’s only milking cows!” Add another third on for my rough estimate of total dairy herd – 6 million. Now add say 5 million beef cattle. Ta da! That’s 11 million very large bovine eating machines. That’s a lot of grass. That’s a hell of a lot of poo – a cow produces around 11 tonnes of it a year. That’s about 121 million tonnes of cow manure produced every year in New Zealand. (This is my own rough estimation. Not all cows poop the same).
121 million tonnes, let’s reflect on that for a minute…
– Weighs the same as 121 million 1990 Honda Civics
– 121 x more grain than is produced in NZ each year
I’ve been told that cows produce two-thirds more manure than is required to fertilise and replenish it’s food supply. So it’s understandable why we have such problems with runoff issues in this country. Add to this no natural native excrement-dwellers to go to work and help break this shit down. Thank goodness the mighty dung beetle army is on it’s way to help remediate. Because left to decompose, manure is a powerful emitter of greenhouse gas emissions.
The smart solution may be the better management of effluent collection for use as fertiliser and put a lot of it through a biodigester for power generation. Surely NZ could be powered by wind, solar and poo power?
According to the University of Alberta, Canada around 7,500 cattle can produce 1 megawatt (MW) of electricity (1MW can power the average home in the developed world), according to the University of Alberta, Canada. The university also says it would take all of the manure of 6 million cows to fulfill the needs of 1 million homes — or about six cows per home.
There! Energy problems solved.
For more info please read Cow power: the energy and emissions benefits of converting manure to biogas