permaculture

[Lois Grossman <lgrossm2@gmail.com>]

Thanks, Toby, for that very cogent and understandable description of
hydroponics and aquaponics and why they are or are not natural systems. I
agree with your position and with your observation that any line we draw
about what is natural and what is not is arbitrary.


On Sun, Dec 29, 2013 at 3:57 PM, Toby Hemenway 
<toby@patternliteracy.com>wrote:

> On Dec 28, 2013, at 7:50 PM, Steve Hart wrote:
>
> > To now reinforce my argument about Hydroponics and Aquaponics as
> developed
> > synthetic artificial systems they do not play any part in Permaculture
> > because they are in fact synthetic and artificial systems that are not
> > natural.
>
> Okay, wading back into the aquaponics debate (thanks for the
> thought-provoking, Steve!). Two issues here: First, aquaponics and
> hydroponics are very different systems, so to me, saying them in the same
> breath, as though they were slight variations of the same thing, suggests
> some confusion over what they are. The main similarity is that they both
> use water and pumps, but then, so does all agriculture.
>
> Hydroponics is a high-input, open loop system that relies on a prepared
> nutrient salt solution that directly feeds plants, in which there is no
> ecology or decomposition cycle. Roots are nearly always suspended in the
> solution (much like mangroves and many wetland plants, ahem.) Wastes
> accumulate and must be flushed away. Nutrients must be supplied in gross
> excess as water-soluble salts. Plants are the single yield.
>
> Almost none of that is the case for aquaponics. It is a low-input, closed
> loop system, very different. Fish food is the primary input, though I know
> of systems that use almost no purchased fish food. The nutrients come from
> manure, just as in organic farming, which is converted by decomposer
> microbes to plant available form (just as in the wild) and the plants are
> usually grown in crushed rock (the base of all soils) wetted by a solution
> of nutrients from manure and decomposers, just as in ground-grown or potted
> plants. Wastes are recycled within the system, which is better than many
> agricultural systems that contaminate groundwater with manure and other
> fertilizers. Plants, fertilizer/manure, and fish are the yields, as well as
> a decomposer ecology.  It uses rock, water, and decomposing organic matter
> to hold microbes and deliver nutrients just as ground-based growing does.
>  Electricity input is no more significant than most irrigation systems.
>
> The principle distinction from in-ground growing is that it's done in
> crushed rock rather than dirt. That is, the rock is not as heavily
> weathered as in native soil, and there is no humus formation. But since
> aquaponics is a nearly closed system, unlike the open loops of ground
> growing, there is no need for the mineral storage of humus. Aquatic
> ecosystems don't need humus; ask any coral reef or estuary. Humus is
> nature's way of retaining carbon and minerals when metabolism and leaching
> are constantly draining them from the system. Carbon and mineral loops in
> aquaponics are largely closed other than losses to harvest, and rock
> provides the colonization sites for microbes that humus usually provides,
> so humus's function is provided for. Microbe populations are as large, or
> larger, as in soil systems. Yes, it uses pipes, pumps, electricity, and
> tanks, but so does all agriculture other than dry farming.
>
> So I would never lump hydroponics in with aquaponics; they are very
> different. Aquaponics retains about as many features of wild systems as any
> agricultural system does. Hydroponics eliminates soil ecology and, usually,
> rock-based growing media, which takes it farther afield than I want to go,
> personally.
>
> Second: the distinction between artificial systems and natural systems is
> an arbitrary line that can be and is drawn anywhere. It's a useful tool,
> but it's a human (and thus artificial!) construct. All agriculture is
> artificial. Irrigation is artificial--nature relies on natural rainfall, so
> it's artificial to use pipes and pumps to deliver water. Domesticating
> plants and animals is artificial. Fertilizing with manure--let alone
> machine-crushed rocks and former marine sediments--instead of relying on
> natural soil fertility and the random droppings of wildlife is artificial.
> Making and spreading compost is artificial. A greenhouse is artificial.
> Planting a seed at a prescribed depth, spacing pattern, and time is
> artificial. Cultivating soil is artificial. Grafting is monstrously
> artificial. And on and on. The line is arbitrary.
>
> Some people draw the line at hunter-gatherer lifestyle. Others practice
> "natural farming" and eschew many common farming practices. Others don't
> draw a line anywhere and eat processed powders. For growing food, I draw
> the line at the absence of soil ecology and prefer food as grown instead of
> processed. But I have no problem with pipes and pumps and growing in a box
> that holds crushed rock instead of a highly amended soil mix.
>
> Philosophers much more learned than me have debated the natural versus
> artificial question for centuries, so I will leave most of it to them. But
> this stuff is fun to think about.
>
> Toby
> http://patternliteracy.com
>
>
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