Jun 15, 2005
Food forever, for nothing
At this point in the IFWMS, raw manure, once rich in organic matter, has been stripped substantially in two processes. In the digester, it yielded biogas and in the basins, chlorella. There is little in the basin residue that is unstable and seeking oxygen. So, when it is finally let into large ponds stocked with a colony of diverse fish, it does not go seeking scarce and valuable oxygen dissolved in water; instead it enhances prolific growth of different kinds of plankton, which are fish food.
When raw manure is dumped into the water as in traditional Chinese systems, it competes for oxygen, impedes the penetration of light and poisons the water. If the manure were composted, nutrient recovery is only partial. The fish pond in the IFWMS, on the other hand is a self-sustaining factory . Waste from fish in the upper colony is eaten by those is the lower, and finally a small residue descends to the bottom. This enriches the entire pond in a beneficial way. Convections or nominal agitation keep nutrients in circulation. When grain or plants are grown on the surface, they need neither fertiliser nor irrigation.
A more dynamic aquaponics is also possible, where nutrient rich water is led through narrow troughs. As they flow they give up nutrients to roots of plants suspended in the troughs. At the end of the run, whatever suspensions remain are cleaned up by plants like lemna, azolla and pistia.The water is now good enough to be recharged into the aquifer.
In another side-play, Chan mixes the sludge from the anaerobic digester with algae, macrophytes and crop residues and sterilises them by steam. The compound is then injected with spores for growing mushrooms. The process of growing mushrooms breaks down most of the compound into edible matter for livestock. What remains can be further used for culturing earthworms, and making vermi-compost.
Chan and Pauli believe eternally sustainable agriculture is possible with zero inputs. It might prompt the question: “All this forever, from nothing? Where does it all come from?” An accurate answer would be: “From the heavens via sunlight.”