* Urban Agriculture
Hydroponics
Hydroponics is probably the most widely used term for growing plants without soil (Hydroculture). A mineral nutrient solution is used to deliver water and nutrients to the plants through a pumped system, either to roots directly suspended in the solution or supported in inert media such as clay pellets or rockwool.
Hydroponics itself has a number of derivative techniques including:
Nutrient Film Technique (NFT) - a continuous flow of nutrient solution is passed across the roots as a shallow stream, which is recirculated, allowing the roots to be exposed to an adequate supply of water, oxygen and nutrients.
Ebb & Flow - nutrient solution floods the system and is allowed to drain away alternately, keeping the growing medium flushed with nutrients and air.
Deep Water Culture (DWC) - plant roots are submerged completely in nutrient solution, which is oxygenated by an air pump and porous stones.
Aquaponics
Aquaponics is a symbiotic system that combines raising aquatic animals (typically fish) and hydroponics. Water and waste from the aquatic animals is fed into the hydroponic system, where the waste products are broken down and used by the plants as nutrients, thereby cleaning the water which is circulated back to the aquaculture tank. The fish and plants are connected in a virtuous cycle of fertilization and filtration.
Aeroponics
Aeroponics, was originally developed by NASA to reduce the amount of water needed to grow plants in space. Plant roots are sprayed with a fine mist of nutrient solution, either continuously or intermittently, and in doing so use less water than in hydroponic systems and much less than in traditional farming techniques.
Aeroponic systems can be further subcategorised into:
Low Pressure Aeroponics (LPA) - a standard pump and sprinkler heads are used to deliver large water droplets to the plant roots. These are often run continuously in a similar manner to NFT hydroponics.
High Pressure Aeroponics (HPA) - operating under pressure typically above 80psi, HPA systems deliver much finer droplets (of 50 microns or less in diameter) by atomising the nutrient solution as it passes through small apertures in the delivery system. High Pressure systems are typically run discontinuously, at set intervals. Plant roots can absorb the finer droplets faster, accelerating growth.
Fogponics
Fogponics (AKA Ultraponics) is a subset of aeroponics where even smaller droplets (1-25 microns) are created by vaporising the nutrient solution, using an ultrasonic transducer, to form a evenly distributed fog. Plant roots can absorb the finer droplets even faster, promoting fast growth, and the evenly distributed fog helps prevent any dry zones which may arise when using an aeroponic misting system. Fogponics does not require pressure-rated equipment as with HPA, but does require regular cleaning to prevent the transducer from clogging.
Ponic Panic
Ponic Panic is a term coined by MIT Open Agriculture Director Caleb Harper to describe the confusion surrounding all the different types and variants of soil-less growing…
I see what he was talking about!
Links
Glossary of Vertical Farming - Association for Vertical Farming
Hydroponics Wiki - Wikipedia
Aquaponics Wiki - Wikipedia
Aeroponics Wiki - Wikipedia
Figuring Out Fogponics - Maximum Yield
Caleb Harper: This computer will grow your food in the future - TED