I think this is an excellent point. Here is how I understand it.
If we don't harvest the fertility off a given piece of land, then the
external inputs (sun, water, air) will serve to make it more fertile
year on year. The sustainable amount of fertility to be able to be
removed from the land is exactly the surplus over and above that to
maintain the exact fertility. Less the amount of energy used to harvest
and move the nutrients from one place to the next. (How you account for
this when using fossil fuels I have no idea - but if you were using
human and animal labour, then they would have to be fed from this
system, not and external system)
If you have to do anything extra to the extensive area, even
periodically, that is not actually supplied by that area, then it is
simply not sustainable. (It might be *more* sustainable, but it is not
actually sustainable). For example, if you have to plough (let's just
say - without worrying whether this is the right thing to do), then the
animal energy would have to come from that field as well.
I imagine that the amount of that surplus would be quite surprising
(and obviously variable depending on time and location), but an example
of how devastating it can be if exceeded is in my country where early
farmers would simply collect forest litter for their fields. They
destroyed the forests they collected from.
But with this system you can't actually say 'I grow tomatoes on 1/2
acre'. You really grow tomatoes on 5 1/2 acres. Plus the few cubic
metres of North Sea oil fields to cover off the tractor.
The beauty of the Ecology Action system is that it is unarguably cut
and dried (even if it is labour intensive). You eat out of the garden,
you use that energy to tend the garden, and all of the fertility is
harvested in the garden to be added in the next crop. The surplus is
also easy to calculate. It is the energy that is generated by the food
that is not returned to the garden in the form of labour (or humanure
and dead bodies if you want to be more accurate). This obviously
includes food sold, as well as your own game of golf.
And you don't have to get your head around calculating the fossil fuel
equivalent of mowing the 10 acres. And even if you could, what are you
going to do with it? Send the cut grass to BP and tell them to put it
in the oil wells and re-extract it in 10 billion years?
Mike
pbunch@cox.net wrote:
On one level I am thinking out loud about our local conditions. On another I am trying to understand the implications of our methods for long-term global sustainability. I don't mean to sound argumentative in a negative way.
Clearly importing nutrients from neighbors is a mid-term solution but what will the situation be if everyone in a given area is recycling the nutrients present in their systems? I suspect they will not give them up at a reasonable price. While good soil structure and a healthy flora and fauna provide optimal condition for local nutrient cycling, nutrients are inevitably lost to leaching and where produce is sold they are exported from the farm with the vegetables and other products. Sustainability is a long-term project and things like potassium and easily leached trace minerals may become limiting factors. Calcium also can be a problem in high rainfall areas. The natural geochemical cycles are the ultimate constraints on what we can do. Mass is conserved.
Eventually, and perhaps sooner than later the throughput via the human population has to be addressed. I doubt if 6 billion people, with 9 billion in the near future, can be supported even with the best methods.
---- Tradingpost <tradingpost@lobo.net> wrote:
Intensive gardens can also be the cash crops, as it is with us. Since we don't have fields we import free amendments and mulch for intensive. In both cases nearby farmers have excess to get rid of and it gets recycled. The sources don't have to be esp fertile. Fertility - the crumb sructure and biologicals - is built up in the beds.
paul tradingpost@lobo.net
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