permaculture

[Toby Hemenway <toby@patternliteracy.com>]

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