permaculture

[KAKerby@aol.com]

John, I had to chuckle when I read your note at the end about Ireland's  
dampness and resulting "fungal abundance".  We have much the same climate  
here as you do.  We're not quite as far north, but we've got l-o-n-g, damp  
autumn/winter/spring, with typically only a few short weeks of warm dry  
summer.  We could quite possibly be the mildew capital of the continental  
USA.  
Early blight, late blight, fungal this-n-that are all very common  here for 
just about everything and anything that grows.  
 
Happily, there are a variety of options in aqupaonic systems.  One of  my 
favorites is to inoculate the system in advance with beneficial  bacterial 
and fungal colonies, so that any wayward spore or germ has a lot of  
competition, right from the start.  That can be done either in the root  zone 
or 
foliar sprays or both.  One very popular choice is compost tea,  which I 
believe 
someone else either mentioned or asked about earlier in this  conversation. 
 Well made compost tea is just brimming full of beneficial  goodness, and 
it can safely be used in aquaponic systems. 
 
Another of the strategies with aquaponic systems is to have a really strong 
 diversity of plant populations, so that no one plant species is host for  
something which will cause problems.
 
A third option is to have lots of moving air through the growing  area.  
The stereotypical aquaponics system is generally illustrated as  being within 
a greenhouse, and most of the systems I've seen or toured had fans  that 
blew a phenomenal amount of air through that canopy.  If there were  fungal 
spores moving through, they just kept on moving.  That also helped  keep 
humidity down even with the fish tanks in near proximity.  Some  climates can 
get 
away with aquaponics systems set up outdoors, or with only  partial roofing 
(such as the UVI system).  I don't know what sorts of  tropical nasties 
they've encountered but they must have their own special  population of pests 
down there too.
 
I haven't done a keyword search in Google to see what sorts of disease  
problems the various universities have had in their setups; I'm sure some of  
them have written up articles about this-or-that issue.  That might be an  
interesting day of reading for the next rainy day we have here, which will be 
 
sooner than I'd like.  But yes, in general, there are multiple options for  
aquaponics, just like for other forms of gardening and/or ag, which either  
prevent, minimize or mitigate damage from fungal, bacterial or viral  
disease.  It would be hard to make blanket recommendations about which  ones 
would be the best or most appropriate, since there are so many  other 
variables 
involved.
Kathryn Kerby
frogchorusfarm.com
Snohomish, WA
 
 
In a message dated 10/9/2012 4:28:43 P.M. Pacific Daylight Time,  
dhondt@eircom.net writes:


I  was obviously too fast again when I called a water environment basically 
 
anaerobic. That would only be the case in a static situation. Moving water  
can have enough oxigen to enable salmon to perform very powerful  leaps.
However, if you had numbers of micro-organisms in water as high as  in good 
soil your water would be anaerobic and it would look rather  unclear and 
murky.
Those huge numbers in soil are important because in  a good ecosystem like 
good soil, bacteria and fungi have very much closer  relations with plants 
than just turning amonia into nitrate. It is known  that micro organisms 
exchange complex molecules like amino acids and  vitamins (B12 has been 
known 
for this for decades) with plants for plant  made sugar. In some places 
like 
India people used sugar as sole fertilizer  and saw no lack of nitrogen. I 
can well believe that for I used Sitka  spruce saw dust (with virtually no 
nitrogen) on top of rock and could not  find nitrogen being a limiting 
factor. Of course we seldom have a problem  with too little rain here in 
Ireland and that helps.
Fungi/mycorrhizae  live partly inside plant roots, exchange molecules and 
information and are  known to protect plants from environmental stresses 
like 
acid rain and  diseases caused by other fungi and bacteria.

I love my soil ecosystems  for they enabled me to get rid of potato blight 
and crucifer clubroot  without any chemical intervention and even without 
rotating crops much for  20 years. What do you do when your aquaponic 
system 
develops a disease  problem? You probably have a better chance in Tassie or 
the US but here in  Ireland blight and other fungal spores are everywhere. 
Still, how would  you solve disease if it occured?
John


G'day John &  others,

If I read John's reply correctly, he seems to imply that  aquaponics 
systems 
are anearobic. Not so. The bacteria that convert the  ammonia to nitrites, 
and other species that convert the nitrites to  nitrates, all require 
oxygen 
to thrive. Hence the use of air bubblers in  most succesful system to get 
the 
dissolved oxygen (DO) levels to the  maximum. And to prevent the fish from 
going belly up, of course. DO is  VITAL to the operation of aquaponics. 
This 
is further mitigated by system  design, e.g. the commonly used flood and 
drain system gradually floods the  growing media with poop water, then the 
water flushes away quickly which  effectively "sucks in" O2 from the air 
above the growing bed. Then the  bacteria go to work to do the conversions 
so 
that the plants can thrive.  Without O2 (by definition, anearobic 
conditions), the bacteria die ->  poop remains poop -> fish die of ammonia 
poisoning. BIG  PONG.

Areas that get clogged up in the grow beds, e.g. tomatoes have  vigorous 
root 
systems that sometimes lead to "dead" spots in the beds, get  anaerobic. 
When 
you stick your hands in there, it pongs. As you would  expect. These dead 
areas mean that the overall conversion efficiency of  the grow bed (i.e. 
natural filter) becomes less efficient. A regular  testing regime (e.g. 
weekly) for ammonia and nitrates will show you how  efficiently the 
conversion is happening, and will point out when there are  problems in the 
system. That is one reason for instance why sand is a  Really Bad Growing 
Medium in aquaponics, because it simply clogs up with  poop and plant roots 
too easily.

Earth worms are often put into the  growing beds, where they work further 
on 
the sludge and enable the most to  be made of the nutrients contained 
therein.

Lastly, there are very  few places on this planet where the perfect combo 
of 
soils & climate  occur. (I happen to be in one such place, being NW 
Tasmania.) So even in  organic soil-based ag, one would have to import 
micronutrients in the form  of rock dusts, kelp meal etc. to get the soil 
in 
balance. This can also be  done in an aquaponics system. Most systems are 
run 
in the pH range of  6.0-6.2, which means that rock dust amendments will get 
dissolved by the  slightly acidic water, thereby making the nutrients 
avaliable to the  entire system (plants & fish). Quite commonly, sea weed 
extracts are  also added for the same purpose.

Cheers

Pierre  Marx



>________________________________
>From: John  D'hondt <dhondt@eircom.net>
>To: permaculture  <permaculture@lists.ibiblio.org>
>Sent: Tuesday, 9 October 2012  8:22 AM
>Subject: Re: [permaculture] pc  aquaponics
>
>
>My problem with aquaphonics is not just  disolved chemicals aka nutrients.
>Soil is an ecosystem consisting for  at least ten % out of microorganisms 
>and
>often a lot more. To a  large extend these soil organisms are aerobic. It 
is
>as good as  impossible to maintain a large aerobic community in  water.
>john
>
>> 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  k
now
>> 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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