In this week's New Scientist magazine (23/02/13 page 5) it tells us that the UN Environment Programme has revealed that 80% of the fertiliser use in farming globally is for meat production. Pastures are fertilised to boost grass production and for fodder crops. I guess that by 'fodder crops' they mean maize and soya, and also wheat and barley (I'm not sure if soya requires nitrogen fertiliser, as a legume perhaps it does not).
Half of the fertiliser put onto the land isn't used by the crops. It runs off the land into the rivers and seas and causes environmental damage. The solution, according to the authors is for fertiliser to be used better and for us all to eat less meat.
This figure of 80% is a surprise, and it fits in with what we already know about how much of the crops grown - mainly maize and soya - are fed to farm animals. It's also mentioned in the Guardian article about this UN report (18/02/13).
In the Guardian article it says that the authors of the report are not suggesting that we give up eating meat. They are suggesting we become demitarians - eating half as much meat as we are used to. I agree with this, but there are a couple of points I'm not so sure about.
The lead author, Professor Mark Sutton, says we should replace most of the meat on our plates with vegetables. Meat provides us with protein and calories, and although we could do with less of both of these, we're probably going to need something to make up for the shortfall if we replace meat with carrots, broccoli etc. Vegetables don't have much in the way of protein or calories, but pulses are a cheap form of protein (and have some calories) and grain in the form of rice and pasta are the cheapest form of calories (and have some protein).
One of the problems in asking people to eat less meat (or less junk food) is that they think they're going to be expected to live off celery and lettuce. They don't have to, they can have tasty rice and pasta dishes. Vegetables are thought of as too expensive for poorer people, which isn't true, but it's easy to see how rice and pasta are the cheapest foods, much cheaper than any form of meat.
Professor Sutton also says that people in poor countries should be 'allowed' to increase their consumption of animal protein. It is true that in some countries people don't get enough protein, although in other poorer countries people do get enough - it's just that they like the idea of eating more meat. I don't see why it has to be animal protein though. Since the UN changed it's official estimate of how much protein people need downwards in 1985 we've known that people don't need that much of it.
People who aren't getting enough protein are usually people who aren't getting enough food. If someone gets enought calories from rice they will be getting almost enough protein. It doesn't take much in the way of beans, peas or lentils to give someone both the quantity and quality of protein that they need. In Indonesia people were encouraged to eat less tempeh (a traditional food deriving from soya beans) and more chicken. I think that was wrong. Protein from tempeh or tofu, or beans or lentils, is just as good as animal protein. It's more efficient to convert soya beans into tempeh or tofu than into chicken and pork.
Professor Sutton says that chicken and pork are the meats that cause the least amount of environmental damage. "Chicken is one of the most efficient [meats] as it grows very quickly and you can collect the manure," he says. Chickens have one of the best conversion rates of grain and soya to meat. Better than pigs, so let's not encourage more pig keeping. I would expect eggs to be an even better way of getting cheap protein than chicken meat. Also, freshwater fish and things like crayfish are even better than chickens. Mammals and birds use up a lot of their calories in generating heat internally, so cold-blooded animals are even better converters of plant protein into animal protein.
So I agree with the principle of demitarianism, but there should be more emphasis on grains (like rice and pasta) and pulses. We shouldn't fall into the trap of thinking that food falls into a spectrum with affordable junk food at one end of the spectrum and unaffordable fruit and vegetables at the other end of the spectrum. Also, I don't think we should encourage the poorer countries of the world to produce more animal protein.