permaculture

[Toby Hemenway <toby@patternliteracy.com>]

Well-aerated, nutrient-rich water can grow vastly more microbes than any 
soil. I used to run a fermentation lab, so I've done it, easily. This is why 
wetlands are so important--and they work because wetland plants pump out 
oxygen at far higher rates than most terrestrial plants, and nutrient 
diffusion rates in water are far higher than in soil. Plus soil is mostly 
rock or carbon, which displaces bacteria, while water doesn't displace 
them--the sheer density of microbes in water can be far higher. The few 
billion bacteria per gram of healthy soil are a fraction of what a healthy 
wetland or an aquaponics system can achieve.

Like any system, aquaponics is not appropriate for every situation. But in 
places where land is scarce (cities), conditions are unreliable (many 
places), technical resources are more available than soil, and a number of 
other situations, aquaponics can allow food--and dense protein--to be grown 
where it otherwise can't. 

You can get rid of fungi and other diseases more easily than in soil because 
you can circulate a treatment through the entire system very quickly or even 
replace the water, unlike soil.

I'm grateful to Kathryn K for staying so level-headed and reasonable in the 
face of some assumptions not well based in fact. I used to have a strong 
prejudice against aquaponics, but it pretty well dissolved after I learned 
more about it. I'm awfully fond of soil-based systems, but aquaponics has its 
advantages in some places. It's a useful tool.

Toby
http://patternliteracy.com


On Oct 9, 2012, at 2:19 PM, John D'hondt wrote:

> 
> 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
> 
>