What Permaculture Doesn't Talk About

I just finished reading an article by Vaclav Smil in the July, 1997 issue of Scientific American, titled "Global Population and the Nitrogen Cycle." There is some very important stuff in here. Take this paragraph, for example:

"The combination of recycling human animal wastes along with planting green manures can, in principle, provide annually up to around 200 kilograms of nitrogen per hectare of arable land. The resulting 200 to 250 kilograms of plant protein that can be produced in this way sets the theoretical limit on population density: a hectare of farmland in places with good soil, adequate moisture and a mild climate that allows continuous cultivation throughout the year should be able to support as many as 15 people."

The article goes on to say that historically the norm has been closer to five people supported per hectare of organically farmed land. This is due to things like periodic droughts and insect plagues, as well the need to grow non-food crops on the same land (for clothing, medicine, etc).

Now a hectare is roughly two and a half acres. And an acre is slightly smaller than a football field. So this means that to keep somewhere around 10 people alive using organic methods today, you would need to cultivate two and a half football fields worth of food in a climate that allowed year-round cultivation. Think about that. And as you do, here is a visual aid, courtesy wikipedia: an image of an acre overlaid on a football field.



To sum up the situation, here is another quote from the article:

"Understanding these realities allows a clearer appraisal of prospects for organic farming. Crop rotations, legume cultivation, soil conservation (which keeps more nitrogen in the soil) and the recycling of organic wastes are all desirable techniques to employ. Yet these measures will not obviate the need for more fertilizer nitrogen in land-short, populous nations. If all farmers attempted to return to purely organic farming, they would quickly find that traditional practices could not feed today’s population. There is simply not enough recyclable nitrogen to produce food for six billion people."

How come you never hear this stuff in permaculture workshops?

And lastly, here is a pdf of the full article if you are interested.