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  • From: venaurafarm <venaurafarm@bellsouth.net>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] pc aquaponics
  • Date: Mon, 08 Oct 2012 00:25:35 -0400

On 10/7/2012 9:52 PM, Scott Pittman wrote:
I too have serious misgivings about aquaponics. It is always presented as
some kind of perpetual motion machine that provides for all its needs within
the system, which I doubt. I also do not believe that it could possible
have the nutrients necessary for providing wholesome and nutritious
foodstuff. We are talking about the primary nutrient source being fish dung
in this closed system, where does the selenium, calcium and phosphorous come
from? The co-evolution of plants with soil organisms and minerals has
created the human nutrition story and without soil I think the actual
nutrient content will be woefully inadequate.

I would never try to grow food for myself in an aquaponics system unless its nutrients came from extracts of soil-based systems (don't quite know how that would work given the anaerobic aspects of aquaponics systems. I did find through a Google search a site with pictures of a soil-based aquaponics system but they were growing ornamental aquatic plants in submerged perforated barrels with a soil mix in them. The root crowns of the plants were slightly above water level.

I would love to see some data on nutrient content of hydroponic vs soil
based vegetables.

There is probably no comparison with the nutrient dense food crops grown in enriched soil with balanced nutrients and minerals.

I would also point out that both the rice paddy system and chinampa systems
are soil based systems with a lot of water to maintain growth they are not
by any means hydroponic or aquaponic. You might also throw in the fast
disappearing mangroves as an example of aquaponics but again you would be
wrong.

In Eritrea they are developing an array of sustainable farming systems that use sea water, They impound water in lagoons and grow shrimp in them. That nutrient-rich water is released down stream to fertilize and irrigate salt-tolerant land based crops. These crops are used to human as well as livestock feed and to make rope or cloth. They are also propagating, planting and harvesting mangroves for firewood, livestock feed and construction wood. They are not reducing the populations of mangroves along the coastline where their project is located. There is a PBS documentary about this well worth watching, maybe viewable online or for $$$ for the dvd.

LL





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