Yesterday, we saw a 'retirement home for chickens'; today we have yet another urban agriculture project by a group of students from New Zealand. "Pod" is a household 'fogponics' gardening concept by a quartet of second-year Industrial Design students (Adam Ben-Dror, Nick Johnston, Casey Lin and Robert Skenea) at Victoria University of Wellington, who have adopted the name Greenfingers for the recent term project.
They researched several other options for a nutrient/watering system before arriving at fogponics, a variation of aeroponics, which differs from hydroponics in that it doesn't require a growing medium.The fogponic system is similar to aeroponics in that the nutrient solution is vapourised, allowing it to be more efficiently absorbed by the roots of the plant. In fogponics an ultrasonic fogger to create an extremely fine mist. The optimum particle absorption range for plant roots is between 1 and 25 microns in size, and ultrasonic foggers typically create mist from 5 to 10 microns.
Fogponics require little maintenance to the system, with the primary thing being refilling the nutrient solution as it is absorbed by the plant, as well as periodically cleaning the ultrasonic fogger as a build up of salts can occur. Between crops the growing medium that is supporting the plant also needs to be replaced to remove all traces of the previous crops. The typical lifespan of a ultrasonic fogger is around 6000 hours, meaning it would need to be replaced 2-3 times a year, if continuously active.
The fogponics system is an interesting alternative to previously-seen watering systems, and the Greenfingers blog offers valuable insight into the students' research—I'm not sure if the documentation was part of the original brief, but it was certainly worth the effort.