A rooftop sweet-potato hydroponics system provided by NTT Facilities Inc., won an Eco-Products Award in the Eco-Services category on November 26, 2007 from the Ministry of Agriculture, Forestry and Fisheries. The system grows sweet potatoes without soil by circulating water, mixed with soluble fertilizer containing minerals and other nutrients, through the growing unit.

Compared to conventional rooftop greening systems, this system has advantages in that it is light, does not need nursery soil to be carried up to rooftops, and can automatically control supplies of water and fertilizer. When sweet potato plants give off water vapor from their leaves, they absorb large amounts of heat, lowering the surrounding temperature. According to research by NTT Facilities comparing an area covered with sweet potatoes and a non-vegetated area, the daily temperature varies by only 3 degrees Celsius in the vegetated area, compared to 27 degrees in the non-vegetated area.

This system makes good use of the sweet-potato's strengths, such as fast growth, high insulation capability, and ease of cultivation. Sweet potatoes are generally supposed to be ready to harvest five months after installing the cultivation units. Since the system doesn't use soil, it is easily installed on existing buildings. It also provides the enjoyable experience of harvesting the potatoes, as well as an opportunity to learn about related environmental problems.


- Sweet Potato Cultivation on NTT Rooftop to Reduce Urban Heat (Related JFS article)
http://www.japanfs.org/db/1556-e
- 3rd Eco Products Awards Go to Innovative Products and Services (Related JFS article)
http://www.japanfs.org/db/1653-e
- Rooftop Sweet-Potato Hydroponics System Curbs Heat Island Effect (Related JFS article)
http://www.japanfs.org/db/1606-e

Posted: 2008/06/06 08:11:08 AM

TAG Food/Water , Global warming , Non-manufacturing industry , Technology