Closing the nutrient loop.

In an urbanizing world, growing some of our food in cities can make our communities both more sustainable and more secure.

Every day, an armada of petroleum-fueled trucks, trains, ships, and planes hauls perhaps 20,000 tons of food into New York City - a mobilization comparable in scale to that of a military invasion. In the course of the day, a large part of that cargo is converted into human energy, flesh, sweat, carbon dioxide, and heat. Most of the rest - including some 10,000 tons of organic garbage and sewage - is hauled back out of the city by a second, different, armada. The organic waste does not end up anywhere near the fields, orchards, or fisheries that produced the food and is not recycled back into the land. A large amount of it is exiled to landfills, permanently sealed off from the earth's ongoing life.

The same pattern prevails in most of the thousands of other cities on the planet, except that in many of them the waste is not hauled or piped away but dumped directly into rivers or bays, where its unnatural concentration causes such ecological disruptions as algal blooms and fish die-offs. In very few cities is any significant portion of the nutrient flow returned to the land from which it came, as an investment in future production. Unlike healthy ecosystems, in which nutrients are largely recycled, the typical urban system is a dead end. The cumulative effect is a gradual depletion of the places where the products originate, and a poisoning of the places where the wastes ultimately concentrate.

This massive shifting of nutrients from rural to urban areas has already diminished the vitality of many of the planet's most productive croplands, grazing lands, and fisheries, and the process could accelerate as more and more of the human population concentrates in cities in the coming decades. It is also creating a dilemma: how to feed the growing number of people who are far removed from their main sources of food, without unbalancing and collapsing the ecosystems - both nearby and distant - on which those people ultimately depend. Political leaders have been slow to recognize and respond to this dilemma. But in many cities residents are not waiting. Both with and without official sanction, millions of people are now producing food right where they live - in empty lots, on rooftops, and in their own backyards.

At first glance, farming may seem among the least suitable of urban activities. But, in fact, throughout much of the world, cities and farming have an ancient relationship. In the classic The Economy of Cities, Jane Jacobs argues that agriculture is actually an urban invention, developed in cities which were first founded as centers of trade. She observes, for instance, that the first medieval system of crop rotation typically centered around towns and took decades or longer to reach the most isolated rural areas.

Indeed, the integration of food production and urban life may once have been universal. Grain cultivation and domesticated animals were present in the earliest known city, Catal Huyuk in Anatolia (now Turkey), from its inception around 7000 B.C. In pre-Columbian Mexico, the highly productive system of Chinampa agriculture, consisting of raised beds surrounded by canals, provided most of the food, flowers, and fibers consumed in the Aztec capital of Tenochtitlan. And in Europe, field crops were grown both within and outside the walls of medieval cities.

In the industrialized world, urban farming largely disappeared in this century. But in the developing world it has persisted, and since the 1970s has even shown signs of a resurgence. According to the most widely accepted estimate, about 200 million urban dwellers now participate in urban farming, providing 800 million people with at least some of their food. Farmers in Accra, Ghana, supply the city with an estimated 90 percent of its vegetables, including radishes, cabbage, and cauliflower. Farmers in Singapore produce 25 percent of the city's vegetables and 80 percent of its poultry. (Much of the grain needed to feed the poultry, however, is brought in from the countryside.) In Berlin, more than 80,000 gardeners lease plots on land where buildings were destroyed by bombs in World War II.

Where in-city food production is extensive, it can also play an important role in municipal waste management. In China, human waste is treated and sold to farmers as fertilizer. In India, sewage-fed lagoons produce about one-tenth of the fish consumed by Calcutta. In the more industrialized countries, concerns about disease have put up barriers to using human waste in agriculture - barriers which contributed to the separation of farming and urban living in the first place. But the development of techniques for safely reusing urban wastes may now make it possible to bring farming back into close proximity with people.

Meeting urban food needs

The global demand for food is expected to grow at least as fast as if another Calcutta or Los Angeles were to appear on the planet every two months for the next several decades. Yet, the world's capacity to increase supply is approaching its limits. Recent rises in grain prices, combined with declining global stocks, may well be a harbinger of future food shortages. If the scarcity that many foresee becomes a reality (see "Facing Food Scarcity," November/December 1995), the impacts won't be spread evenly. It is in the fast-growing cities of the developing world where tens of millions of impoverished migrants are concentrating that the increasing competition for food will be felt most acutely. As those cities expand, the problem of food security could balloon into a widespread crisis and a dominant issue for urban policy. Today, although urban agriculture plays a relatively small role in total food production, it provides a crucial safety net for many of the people most at risk. With supportive policies, it is likely that this role could be significantly expanded.

Today's problems of hunger and malnutrition are less a function of production than of distribution, since the world's farmers still produce enough food to provide all of humanity with an adequate diet. But the poor are increasingly squeezed out of the market by the growing numbers of wealthy consumers - and the gap is growing not only between rich and poor countries but between the rich and poor within countries, and even within cities. (As wealth becomes more polarized, the ranks of both rich and poor are increasing.) Those who are newly affluent are changing their eating habits, demanding more meat. And as more grain goes to fatten beef, less is available for direct consumption (as plain rice or bread, for example), and that pushes up prices that shut out rise poor even more. Already spending the bulk of their income on food (at least 60 percent among low-income families in Bangkok and as much as 90 percent in the poor neighborhoods of Bolivian cities), some of the urban poor are being forced to look for alternative sources. What they are finding may have unanticipated value for people at all income levels.

In Uganda, a study by University of Wisconsin researcher Daniel Maxwell found that some 35 percent of the households in Kampala produce their own food and save substantially on food expenditures. On rented or informally occupied land, they grow cassava, sweet potatoes, coco yams, plaintains, maize, and beans. The nutritional status of children of low-income families that farm in Kampala was found to be no different than that of the children of wealthy families, and better than that of non-farming low-income families.

City gardens provide an important source of income, as well. In Bogota, Colombia, a cooperative of more than 100 low-income women produces hydroponic vegetables on rooftops, earning the women up to three times more than their husbands make in semi-skilled jobs. In India, the rich, composted soils of old garbage dumps in the main dumping site of East Calcutta produce 150 to 300 tons of vegetables a day and generate employment for about 20,000 people. And in Accra, the average daily income of gardeners is three times higher than average daily wages in the formal economy. The success of efforts such as these suggests how much larger a role urban agriculture could play in bolstering local economies and food security if governments were to establish policies supportive of the practice.

One measure of this potential is the experience of China, which began implementing a policy of food self-sufficiency in the 1960s. The Chinese have not artificially segregated farms and cities in the way Americans and Europeans have; in fact, the Chinese definition of a metropolitan area includes the surrounding farms and villages that supply a city's food. Advocates of urban agriculture have cited some impressive data, noting that China's urban and peri-urban farmers provide 85 percent of the vegetables and more than half of the meat and poultry consumed in 18 of the country's largest cities, while recycling the majority of those cities' human wastes. But this data is not just the result of using a different definition of "urban." What's significant about the Chinese system is that it acknowledges the need to link nutrient inputs and outputs in a closed, coordinated system.

As China industrializes, however, this system is coming under assault. According to Annu Ratta, a consultant to the International Food Policy Research Institute and the World Bank, the pressures brought by explosive urban growth - soaring land values, high rates of land conversion, and increasing pollution - are breaking up the self-contained cycle. If this trend continues, China will be faced with either the high levels of pollution from human wastes typical of most cities in developing countries or the need to build expensive sewage treatment plants, and its reliance on imported food products will increase. China may be headed for a belated discovery that the system on which it has long relied is the most efficient and economical option after all.

Closing the resources loop

To dispose of the 22,000 metric tons of waste it generates each day, Tokyo is building islands of garbage in Tokyo Bay. The islands are posing a growing threat both to the fish which live in the bay and to the shipping lanes which cross it. In other countries, garbage is collected infrequently or not at all, and piles of it build up on street corners or in abandoned lots. Wherever cities exist, they generate a steady outpouring of organic waste - from food preparation, the defecation of people and their pets, and the clearing of leaves or clippings from yards and parks. Unfortunately, the bulk of the nutrients those wastes contain is lost - either buried in landfills or dumped wherever is convenient.

Because improper management of waste breeds disease, most cities, if they can afford to, focus on simply getting rid of it; they fail to recognize the waste as an economic asset. Because soil nutrients are continuously exported from the fields where they grow to the dinner tables of city-dwellers, farmers are forced to rely on petroleum-based fertilizers to replenish them. However, these manufactured fertilizers do not contain all the constituents necessary for healthy soil (they lack the organic matter and microorganisms provided by natural compost, for example), and continued reliance on them ultimately diminishes the soil's fertility.

Meanwhile, the prevailing means of "getting rid" of the wastes tends to concentrate them in ways that wreak havoc with local ecosystems. As urban populations expand faster than the support systems that make cities work, the unmanaged wastes also constitute a growing threat to the residents themselves. An estimated 70 to 95 percent of all new residents in the cities of the developing world are illegal squatters, the majority living in substandard housing without access to such basic necessities as water lines, sewage systems, and trash collection. According to the World Resources Institute, in 1994 at least 220 million urban dwellers lacked a nearby source of potable water, while more than 420 million did not have access to even the simplest latrine. In the cities of the developing world, an estimated 20 to 50 percent of solid waste is not collected. This combination of careless waste disposal and unprotected water for drinking and bathing has deadly consequences.

Even a small disparity between the amount of organic waste produced by a city and the amount properly disposed of can turn into a disastrous backlog. In the city of Surat in western India, the 2.2 million residents generate 1,250 metric tons of waste each day, but only about 1,000 tons of that is collected. Every day, as a result, the amount of uncollected garbage piling up around the city increases by another 250 tons. In September, 1994, Surat was struck by an epidemic of plague. Authorities found one cause of the outbreak to be the numerous heaps of trash, which provided an ideal habitat for the rats that carry the plague infection.

But even when wastes are collected, the likelihood is that they will be dumped without any sort of treatment, overwhelming the capacity of local ecosystems to absorb them. In the developing world, some 90 percent of all sewage is discharged - along with the fecal coliform bacteria that cause intestinal diseases - directly into rivers, lakes, and coastal waters. These contaminants not only disrupt aquatic ecosystems, but can get into the food chain and eventually make their way back to the people living in the city. The nutrient cycle, instead of becoming an ecologically closed loop, becomes a short-circuited one. In Hong Kong, for example, raw sewage from the city's 3.1 million inhabitants flows directly into Victoria Harbor, causing shellfish contamination that led in 1988 to a hepatitis epidemic afflicting nearly 1,400 people.

It is possible, instead, to restore the organic nutrients in urban wastes to their proper place - the soil - and continue to utilize them to produce the food needed for urban consumption. By reusing wastes for local agricultural production, cities can become more sustainable, retaining their productive capabilities without causing contamination of nearby land, air, or water.

Reusing urban wastes can take a variety of forms. Human sewage, euphemistically called nightsoil, when treated becomes a rich fertilizer that can be applied to agricultural fields. Using nightsoil as a fertilizer is an important component of China's integrated urban agriculture system. For example, in 1991, Shanghai was collecting 90 percent - about 8,000 tons - of the city's human waste each day, treating it, and selling it to farmers in the metropolitan area. Industrial countries recycle sewage sludge, the solid by-product of wastewater treatment.

One particularly promising technology for recycling human wastes produced by cities also provides an important source of food. For more than 50 years, wastewater-fed aquaculture in Calcutta, India, has produced fish for the city. A natural wetland east of the city has been modified into a 12,000 hectare cluster of ponds that grow fish on sewage; the sewage provides nutrients for the algae the fish eat, and the process in turn dilutes the high concentration of fecal coliform bacteria present in sewage. The resulting effluent can then be safely used to irrigate fields. Each day, 22 tons of fish - mainly carp - are produced in the course of treating 150 million gallons of Calcutta's wastewater. The ponds provide at least 10 percent of the city's daily consumption of fish, which are the primary source of protein for Calcutta's residents. It has been estimated that the output could be doubled.

Wastewater-fed aquaculture provides benefits other than food to cities. It also represents a cost-effective way to treat the wastes that are now discharged directly into the local environment - polluting rivers, estuaries, and seas. A 1990 proposal to construct fish ponds similar to Calcutta's in other Indian cities estimated that ponds with a capacity to treat 30 million liters per day could be built for one-fourth the cost of a conventional mechanical treatment plant with a comparable capacity. Not only are the aquaculture ponds cheaper, but the products can also be sold for a profit, reducing total costs further. In Lima, Peru, fish farms fed by partially treated wastewater are expected to recover 100 percent of the wastewater treatment costs through fish sales. Duckweed ponds can also be used to treat wastewater: in Kochcice, Poland, a duckweed pond treats wastewater from 3,000 residents at a cost far lower than that of a treatment plant, and the biomass produced is harvested twice a year and fed to livestock.

Solid waste management can also be facilitated by diverting organic wastes from landfills or dumps and converting them to compost. Of the 26,000 tons of solid waste thrown out by New York City each day, some 20 to 40 percent is organic matter. Composting such material could reduce disposal costs and provide rich soil for urban agriculture. In addition, the three principal by-products of the composting process - heat, carbon dioxide, and water - together with the compost itself, can be used for intensive greenhouse agriculture. As Thomas Outerbridge, the city's former Director of Composting, noted several years ago in The Ecologist, "According to some estimates, New York City could eventually meet much of its own demand for vegetable produce in this way."

New York has recently launched several efforts to capture the benefits of composting. The pilot Food Waste Composting Facility on Rikers Island, a prison facility with 15,000 inmates and 10,000 guards and officers, represents the city's first large-scale attempt to compost a concentrated food waste stream. The facility processes 20 tons of food waste and corrugated cardboard per day, and hopes to eventually use the compost for the island's farm program. Smaller projects to compost several hundred pounds each day are underway at a hospital in Queens and on the City College campus. Robert LaValva, the current Director of Composting, notes that these smaller-scale projects probably make more sense and have a better chance of succeeding since composting, unlike most other kinds of recycling, can be done locally and the end-product can be utilized locally. As his analysis suggests, it may be easier to keep the loop closed when both ends of it are kept in the same locality.

A Survival Technique

More than five billion people will live in cities by 2025, and if present trends continue, almost half of them - as many as the whole population of the world after World War II - will live in chaotically growing districts that are increasingly polluted and afflicted by poverty and social and economic instability. Under such conditions, the problems associated with feeding those cities and managing their wastes seem almost insurmountable. Yet in many ways, living in cities is the most sustainable option people have, since high population densities minimize transportation needs and energy consumption and reduce each individual's impact on the larger environment.

While most experts agree that urban farming is now both viable and desirable, they are contentious about its potential contribution to feeding the world's population. Jac Smit, president of The Urban Agriculture Network (TUAN) and co-author of Urban Agriculture: Food, Jobs, and Sustainable Cities, recently released by TUAN and the UN Development Programme, claims that urban agriculture already produces 15 percent of the world's food, and that it has the potential "to produce one-quarter of the nutritional needs of the global population where they live." Rachel Nugent, the economist who wrote the chapter on urban agriculture in the 1996 State of Food and Agriculture, published by the UN Food and Agriculture Organization (FAO) in October, takes a more cautious view: urban agriculture, while potentially viable and productive, takes much more planning than exists in the cities of most developing countries. "It is not a panacea to solve the most severe problems of food security in cities," she says, and is "at best...a survival technique for the urban poor."

As Nugent observes, the real potential may be determined less by technical constraints than by institutional ones. Many governments continue to discourage the practice - by prohibiting it, or, in some cases, by actually destroying fields in cities. Such responses lead Daniel Maxwell to caution that "calculations about production levels that are technically possible just seem unrealistic..." On the other hand, as the issue gains greater prominence, governments in many cities are beginning to recognize that local food production may be an important component of food security.

What's indisputable is that land suitable for urban agriculture is amply available. According to a study by the U.N. Centre for Human Settlements, up to 50 percent of the total area in many cities in developing countries is vacant public land. Estimates from the early 1980s identified 200 square kilometers of available land in Greater Bombay, 338 square kilometers in Bangkok, and as much as 600 square kilometers in Sao Paulo, Brazil. To put that in perspective, Pablo Gutman has found that in Buenos Aires, a 10-by-10 meter plot, if intensively cultivated, can provide all the vegetables needed by a family of five. Of course, not all of the vacant or "available" land could realistically be turned over to producing food. But large portions could. In greater Bangkok, for example, some 60 percent of the city was officially being used for agriculture in the 1980s. And in Kampala, mapping done by the city's Department of Planning found that 56 percent of the land was being used for agriculture in 1992.

In the more developed countries, too, the potential is large. Berlin's 80,000 gardens are cultivated on 4 percent of the land area. In the United States, as cities sprawl farther and farther from their centers, more space is left unused or abandoned. Between 1980 and 1990, the population of the Baltimore/Washington, D.C., metropolitan region grew 20 percent, but its geographic area increased by four times that amount. Inner cities in the United States are riddled with empty lots, and poor urban planning has left tracts of land unused in suburbs, along highways and around industrial districts, ports, or airports. In Detroit alone, over one-third of the city is vacant.

What took place in the U.S. "Victory Gardens" during World War II demonstrates the extent to which urban gardening can contribute to food production if it is given the full support of public policy. In the early 1940s, in response to the shortages created by the war, U.S. citizens plowed and cultivated nearly all available urban land, including town commons and city parks, green strips around factories, church and school grounds, backyards, and vacant lots. Gardeners at home helped feed their households so commercial farmers could feed soldiers and the Allies. In 1944, those gardens yielded 44 percent of the fresh vegetables produced in the U.S.

In a more recent example, Cuba has begun to promote urban gardening as a way to achieve nutritional self-sufficiency in the face of economic decline and the ongoing U.S. embargo. Food gardens in Havana now supply about 5 percent of the city's food, and officials at the Australian Conservation Foundation, which sponsors an urban gardening project in Havana, estimate that the figure could be raised to 20 percent.

As detractors warn, urban gardening which uses waste for fertilizer can entail more risks than conventional farming. Improperly managed waste can breed the bacteria that cause intestinal infections, compost can attract rats, and vegetables can absorb heavy metals from the soil or air. Where urban agriculture is close to industry, hazardous toxins can be absorbed by the plants. In 1992, in Santiago, Chile, vegetables grown with irrigation water containing raw sewage contributed to an outbreak of cholera. But as Jac Smit likes to point out, the technologies needed to effectively deal with these problems already exist. The aerated-static-piles composting method developed by the U.S. Department of Agriculture in the 1970s revolutionized municipal recycling of organic wastes. And wastewater-fed aquaculture, if the right techniques are used, reduces the E. coli count of the water entering the wetlands from about 10 million organisms per milliliter to only 10 to 100 per milliliter.

Meanwhile, momentum for expanding the practice of urban agriculture is building. At the national level, the Netherlands and Canada are drawing up green plans that include provisions for the support of urban farmers. This year, the United States passed the Community Food Security Act, which will fund collaborative grassroots projects that produce food for low-income and rural communities, allocating $16 million over seven years. Argentina and Peru have national departments, and Buenos Aires, Jakarta, and Mexico City have metropolitan agencies to promote urban agriculture. Even at the individual level, enthusiasm is growing. A movement toward community-supported agriculture (CSA) that started 25 years ago in Switzerland now includes 600 such programs around the world. Urban dwellers purchase shares in a farm's production - receiving fresh produce throughout the growing season and sharing the risks of weather and pests with the farmer. Such programs also bring communities together and restore a sense of connection with natural processes - benefits that are too frequently lost in the asphalt jungle of modern cities.

Closing the Psychological Loop

As cities industrialize and concrete buildings with sewer lines replace shantytowns and dirt roads, the direct connection between humans and nature becomes increasingly obscured, and it is not unusual for children to grow up thinking that milk comes from paper cartons or honey from jars. While in many ways cities are more environmentally friendly than other forms of human habitation, they also separate people from nature and give them the false sense that they exist outside the limits imposed by nature. Urban agriculture can bring nature back into the cities and help restore this connection.

In the United States, city gardens are helping communities reclaim their neighborhoods from crime and pollution, and often the focus is on saving kids from the street. A local urban gardening organization in Washington, D.C., called From the Ground Up, is growing organic vegetables for shareholders, providing produce for farmstands that train low-income residents in business skills, and teaching inner-city youth about nutritional, environmental, and food security issues. This year, the group's eight-acre farm on the outskirts of the city will produce over 110,000 pounds of fresh vegetables.

In San Francisco, high school students are employed at the St. Mary's Urban Youth Farm, operated by the San Francisco League of Urban Gardeners on an old dumping site for spoil dirt and waste concrete. The four-acre site, adjacent to a low-income housing site, now produces collard and mustard greens, potatoes, broccoli, and other organic vegetables, and has approximately one hundred fruit trees that provide food for neighborhood residents and public soup kitchens.

A new book by Patricia Hynes, A Patch of Eden: America's Inner-City Gardeners, documents similar projects around the country. In Philadelphia, for example, a neighborhood called Norris Square, once known as the "Badlands" for its pervasive drug culture, has been transformed by the introduction of Las Parcelas - a demonstration compost project and environmental park containing 16 family vegetable plots, an orchard with peach, pear, and nectarine trees, flower and herb gardens, and a patio for cook-outs. By building a community around growing things, says a local schoolteacher, the residents "can promise [their children] what no amount of income and no amount of security systems, guards, guns, and locks in suburbs and new towns can buy - the hard-woven fabric of neighborhood."

By closing the biological loop, even if only a little, such projects enable food security to bolster a larger kind of security. Seeing the connection between the judicious use of vital resources and the productivity of a local garden can alert urban residents to the existence of a larger connection - between the stability of the whole region's ecology and that of the increasingly hungry city that depends on it.

Research Needs

Though millions of people produce food in cities, much remains unknown about how much potential remains unfulfilled - for increasing the food supply, improving urban economic security, and restoring a form of "common good" to community life. The following areas, especially areas, especially, could be fruitful grounds for further research.

Caloric Potential: This article is not about home-grown tomatoes or lettuce, which have little food energy. But to what extent can people in cities grow the kinds of food one can really live on, such as corn, beans, potatoes, or yams? Studies are needed to determine which combination of crops would produce the highest food value on a lot of given size (say 100 square meters), intensively cultivated, in various climates.

Protein Potential: Protein is tricky, because most of it comes from animals or fish - not easy to contemplate raising in cities. Most fish is from the oceans, most meat from vast rural grazing lands. Yet, many urban dwellers already produce their own chickens, eggs, or fish in urban settings, often in the informal economy for which little data exist. Even more important, however, is determining the extent to which plant proteins can be produced in urban settings, from such crops as soybeans.

Land Use Policy: What incentives exist, or could be created, for cleaning up and using empty lots for growing food? Similarly, what could impel local governments to encourage cultivation of the large amount of "no-man's land" that is now wasted in public tracts along highways or around airports and industrial districts? In the United States, existing policies pull developers centrifugally away from the city, to bulldoze farmland outside the city for new suburbs -drive farms ever farther from the places where their products are used. The question is how to reverse the incentives that now drive people out, so that central city lots become valued locations for new residences, workplaces, schools, recreation, and gardens - short, all the elements of a fully functioning community.

Potential Protection Against Rising Food Prices: In an era of increasing food scarcities and polarizing incomes, the capabilities of the global market to distribute food to the highest bidders worldwide appears likely to drive prices beyond the reach of the urban poor, even in the regions where the crops are grown. A few studies have shown the extent to which local food expenditures can be reduced by doing urban farming for consumption, but more information is needed on what share of the supply could be provided by this means in various regions, and to what extent that share would increase as prices rise.

Conflicting Demands for Water: The water requirements of cities are already in conflict with those of agriculture in many regions. Growing food in cities imposes new demands for water and, presumably, could exacerbate already existing problems of supplying adequate water for household and industrial uses. In what areas can urban farming succeed with natural rainfall, and in what areas would it need supplementary water? A critical consideration is the extent to "grey" water, or waste water from showers and sinks, etc., could be reused in gardens.

Rooftop Technology: The flat roofs of the world's cities what a pioneer urban farmer of the 1970s called a "vast wasteland" of unused space. Extensive research has been done on the possible uses of this space to capture solar energy and rainwater - and, in fact, the technologies of rooftop photovoltaics and rainwater cisterns are in fairly wide use. Since solar energy and water are two of the essential inputs to agriculture, and obvious question is whether synergistic designs can be developed. A laudable challenge to architects would be to design rooftops that combine optimal insulation, passive solar heating, photovoltaic electric power, rainwater collection, and agricultural production.

Pollution: Polluted air or soil could be a serious impediment to growing food in some cities. How can city administrators most effectively make soil-testing and soil-cleaning services available (or mandatory?) to people who want to rehabilitate empty lots? In areas where leaded gasoline is still used, or where lead, PCBs, and other contaminants may be present in soil where buildings have been demolished, what affordable means are available for reconditioning the soil for growing food? It would be especially useful to determine the extent to which the technologies used for toxic waste cleanups, such as bioremediation, could be adapted to routine revitalization of urban neighborhoods.

RESOURCES

Community Food Security Coalition P.O. Box 209 Venice, CA 90294 310-822-5410 (phone) 310-822-1440 (fax)

Cities Feeding People Project International Development Research Centre 250 Albert Street P.O. Box 8500 Ottawa, Ontario Canada K1G 3H9 613-236-6163 (phone) 613-567-7749 (fax)

The Urban Agriculture Network 1711 Lamont Street, NW Washington, D.C. 20010 202-483-8130 (phone) 202-986-6732 (fax) [e-mail] (email)

Australian Conservation Foundation 340 Grove Street, Fitzroy VIC 3065 Melbourne Australia 61 3 9416 1166 (phone) 61 3 9416 0767 (fax)

Toni Nelson is a staff researcher at the Worldwatch Institute.