permaculture

[venaurafarm <venaurafarm@bellsouth.net>]

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