NEW YORK — Growing food in cities isn’t a new concept for the poor.

Rural farmers forced to migrate to urban areas in the developing world in search of work have long turned to their agricultural skills as a way of feeding themselves and their families when all else fails.

It is only recently that urban agriculture has garnered attention in the first world, something many attribute to the growing popularity and romanticizing of small-scale organic farming.

But in the pockets of poverty in the first world and developing cities alike, urban agriculture has more to do with public health and economic development than it does with environmental trendiness. From Bogota to Milwaukee, Cape Town to Philadelphia, Nairobi to New Orleans, urban agriculture is earning a serious rep as a legitimate development strategy.

NGOs, municipal governments and grassroots community groups are increasingly integrating urban agriculture into policies and programs to combat the root causes of hunger and poverty in poor urban areas.

In the sprawling megalopolis of Sao Paulo, Brazil, I recently witnessed how a humble NGO is quietly transforming an entire region of the city by building micro-enterprises out of organic farms and gardens.

Sao Paulo is the world's third largest metropolitan area, trailing only Tokyo and Mexico City in size. In recent decades, Sao Paulo has grown at an alarming rate. As big agribusinesses buy up land that has historically been used for subsistence agriculture, rural Brazilians — particularly those in the northeast — are displaced from their homes and forced to migrate toward cities, particularly those in the more prosperous southern part of the country.

But like many developing cities, Sao Paulo cannot accommodate its rapid expansion. In the favelas ringing the city, crime, hunger, poor sanitation and high unemployment rates are daily threats to struggling residents.

Cidades Sem Fome (CSF), which means Cities Without Hunger, is a Sao Paulo NGO that uses urban agriculture as a tool to address a number of the favelas' health and social issues. The idea is simple: use vacant land to put unemployed people to work by providing them a venue in which to use their agricultural skills.

Hans Dieter Temp, the founder and current director of CSF, was born in Mato Grosso do Sul to a farming family. Growing up in agriculture, he traveled to Germany to pursue a university degree in politics and technical agricultural skills.

When I met Hans in Sao Paulo earlier this month, he took me on a tour that moved backward, from the point of consumption to the source.

Our first stop was a small market stall in one of the city's most notorious favelas. There, local residents hawked the produce from their gardens and those of neighboring favelas. Locals came to stock up on collard greens, tomatoes, onions, peppers, herbs and a handful of crops unique to Brazil. These are foods that are often hard to come by at favela groceries, and they provide necessary nutrients for preventing disease and malnutrition.

Next, we crossed the street to a large urban garden. Neat rows of lovingly tended lettuce, herbs, cabbage, kale, dandelion greens and more spread across the red dirt. A large compost pile sat decomposing aside a row of banana trees, and a chicken and duck coop bordered the garden on one side.

Community members — primarily women — Hans explained to me, tend the rows. By having work so close to their homes, they are able to stay nearby to their children, a welcome alternative to commuting more than two hours in choking traffic to work in the inner-city service industry.

In addition to a source of income, the garden has proved a catalyst of peacemaking in neighborhoods plagued by gang warfare and bitter ethnic divisions. Hans relies upon his staff of four to help set up new gardens, but the training of new gardeners is the responsibility of community veterans. In this way, communities build their capacity to provide for themselves, and the need for institutional assistance is minimized.

In addition, through the sharing of crops and recipes, barriers are softened and often broken down entirely, bringing a stronger sense of community and cooperation in the areas containing gardens.

Next, Hans drove us to his home, an airy apartment in a favela that he shares with his wife, young son and in-laws. Most educated folks would balk at the idea of living among such dire poverty and notorious crime, but Hans understands that living in the community in which he works is vital to building trust and credibility among the population he aims to help.

The NGO's flagship garden is located kitty-corner to his home, serving as a model that he can show to potential investors. We chatted briefly with Carlito, who tends the small plot and vends the fruits of the harvest. Pride in his work radiated from his beaming smile.

Our final stop was the demonstration site, several acres of productive farmland that are also home to three large greenhouses, a creek for irrigation, a seedling nursery, a pond soon to be used for raising carp and tilapia and a caretaker's home.

The ripple effects of CSF's work are numerous and widespread. To name a few: nutrition improves; neighborhoods become safer; women acquire business skills; air becomes cleaner; and money circulates in poor communities.

Hans relies on public/private partnerships to sustain his work and he is finding that, increasingly, big businesses are eager to add a sustainability component to their philanthropic image. As a result, much of the land used for the gardens is owned privately by some of Brazil's largest companies. Land above pipes or underneath powerlines that cannot be developed is fertile ground for agriculture projects.

For skeptics, there are numbers to prove CSF’s success. In only six years, Hans and his staff have set up 21 agriculture sites, providing income for more than 660 favela residents. CSF's determination to equip communities with the skills necessary to sustain the gardens on their own frees up the team to pursue new projects, adding to the prolific nature of their work.

Neither Hans nor I is naive enough to think that urban agriculture can become the sole source of food for metropolises like Sao Paulo, New York and Tokyo. But we agree that it can become a vital component of sustainable urban development, simultaneously addressing a number of complex social, economic and health issues.

Agriculture is a universal language, connecting us all in the need to eat. Thousands of miles from the gardens I tend in Brooklyn, as Hans and I harvested lettuce and kale in the heart of Sao Paulo, I found myself feeling right at home.

Sara Franklin is an independent food systems consultant and freelance writer. Her work focuses on community health, rural-urban development channels, social justice and urban agriculture.