Clovers, the plants with trifoliate leaves and dense flower heads, could be providing a "green dress" to Shanghai's more than 1 million elevated highway pillars in less than two years, city construction officials said yesterday.
The plants won't have to be planted in soil, they said. Instead, the plants will "grow" on the cement pillars, nurtured by a newly developed matrix material that will be affixed to the pillars, they added.
"Once each of the city's elevated highway pillars is covered by the plants, the 'highway greenbelt' will be the equivalent of 100 Shanghai Botanic Gardens, but no soil will be needed," said Tang Gencai, deputy director of the city Construction & Manage-ment Commission's science department.
Financed by a grant of 50,000 yuan (US$6,024) from the commission, six researchers from Donghua University spent the past two years creating the new matrix, which they claim is the world's first that can replace soil and still absorb water and fertilizer.
Zou Liming, an associate professor of material science at Donghua who was the lead researcher, declined to disclose the components of the matrix. Since it hasn't yet been patented, it could easily be copied, she said.
"Unlike creepers that grow slowly and may cause cracks in a structure, clovers with our matrix material can cover a pillar in at most six months while needing little maintenance," Zou said. "The material is made up of an organic polymer whose inside is mixed with clover seeds. Gardening workers only need to supply the plant with water and fertilizer once a month in winter and two weeks or so in summer."
According to the city Gardening Administration Bureau, the millions of pillars in Shanghai whose surface area amounts to 60 million square meters can produce 3.6 million kilograms of oxygen and consume 5.4 million kilograms of carbon dioxide every day.
Zou said while the material was invented in her laboratory, she needs another two years to apply them on to pillars so that she can record the entire maintenance process.
"Such a large area for a potential urban greenbelt will do a big job in depressing the city's heat island phenomenon," said Zhou Hongmei, a senior engineer at the city Meteorological Bureau. Heat islands are where heat is concentrated in an urban environment.
The matrix material can also be developed into artificial grass for stadiums, the senior engineer said.
(Eastday.com.cn 05/31/2001)
