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  • From: Rain Tenaqiya <raincascadia@yahoo.com>
  • To: permaculture@lists.ibiblio.org
  • Subject: [permaculture] farms as nutrient exporters 2
  • Date: Sat, 25 Sep 2004 13:32:34 -0700 (PDT)

There were a couple of points I'd like to "correct:"

1. Municipal sludge is nasty- If the waste stream is properly designed so
that industrial toxins are not entering it and if the sewage sludge is
composted properly with a good C:N ratio so that it gets hot, there will not
be significant toxins or harmful organisms in it. King County (Seattle area)
has been doing this for years and uses it for growing wheat, landscaping, and
forestry. They report that the level of heavy metals in the soil is actually
diluted by adding the composted sludge. Unfortunately, most of the nitrogen
in sewage is in the liquid part, so it is not being recycled.

2. Exporting crops from farms can be sustainable because plants are mostly
water, carbon, and nitrogen- It is common knowledge that soil fertility
declines after only one to three seasons of exporting crops, and this is not
just because of the loss of nitrogen. Phosphorus, potassium, and other
nutrients are mined out of the soil by plants and must be returned (a basic
permaculture principle). Furthermore, in cases where a nutrient exists in
sufficient quantities only in a certain strata of the soil or bedrock
profile, it will be lost forever once plants that are being exported have
integrated the nutrient into their tissues.

Most of the "solutions" to agriculture involve the use of fossil fuels to
move stuff around. Very few advanced horticultural or agrarian cultures have
been able to sustainably farm for more than a few hundred years, and this is
without the use of fossil fuels. Besides the rape of the planet that fossil
fuel use entails, we need to come up with ways of providing for ourselves
once fossil fuels run out. It is pretty sobering when you start to look at
alternatives. It takes a lot of space and work to grow enough apples to
produce ethanol for even very modest transportation use, for example.

Rain


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