Green Roofs - Living Architecture Monitor - Fall 2010 - (Page 26)

RESEARCH INCREASING URBAN FOOD SECURITY WITH EXTENSIVE GREEN ROOFS GROUNDBREAKING RESEARCH SHOWS THE POTENTIAL TO GROW FOOD ON ROOFS USING A NUTRIENT TEA DERIVED FROM HOUSEHOLD ORGANIC WASTE By Stephanie Gaglione & Brad Bass, Ph.D. T o increase food security in urban areas, food and environmental advocates are recommending that cities embrace urban agriculture. As most of the expected future global population growth will occur in urban areas, green roofs, which do not require additional fertile land, offer a very promising approach to increasing local food security and reducing the energy and cost of transporting this food into a city. However, many buildings can only accommodate very lightweight, extensive green roofs that are too thin to maintain a nutrient supply in the growing medium. Nutrients can be replenished using a commercial fertilizer, which in itself will have a large carbon input and an additional expense. Some recent work with lightweight, extensive green roof panels demonstrated that food could be grown on these roofs using a nutrient tea derived from household organic waste. This experiment used an ultra-light green roof panel with less than three centimeters of growing medium in one square-metre panels, manufactured by XeroFlor International. These panels were five-years old and had exhausted their nutrients. The aerobic degradation of household organic waste was exploited to create a high-quality nutrient tea from compost that was evaluated as a replacement for conventional fertilizers. A liquid nutrient source was derived from compost produced from six-to-eight centimetre layers of carbon- and nitrogen-rich organic waste combined with 20 millilitres of an acclimated bacterial liquid to speed up decomposition. Heirloom seeds of Red Russian kale, Bloomsdale spinach, Salad Bowl lettuce, Bronze Arrowhead lettuce as well as

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Fall 2010

Green Roofs - Living Architecture Monitor - Fall 2010
From the Founder - Urban Agriculture
Strata - T.O.’s New Green Roof Construction Standard
On the Roof With…Richard Conlin
Project - Farming for the City
Beekeeping - Diary of an Urban Apiarist
Exemplary Design - GRHC’s 2010 Awards of Excellence Winners
A Green Roof That Moves
Steeped in Ecological Design
Creating Community
A Model of Municipal Leadership
A Green Roof That Works
Like a Grassland Stream
Prairie in the City
Recycling Rainwater
Research - Increasing Urban Food Security With Extensive Green Roofs
Economic Valuation of a Rooftop Food Garden
Grhc Update - Macro-Scale Food Production
New Corporate Members
New GRPs
On Spec - Urban Agriculture — Hero or Hype?

Green Roofs - Living Architecture Monitor - Fall 2010