A Google Earth survey found more than 4,600 urban agriculture sites equaling 65 acres of food production. (Photo by Roman Petruniak/flickr)

By The Associated Press

URBANA - Backyard and vacant lot gardens play a large part in Chicago's total food production.

That's the lesson from University of Illinois researchers who have developed a method to quantify urban agriculture.

In simple terms, John Taylor and Sarah Taylor Lovell used Google Earth images and mapping software to identify sites where gardeners are growing food. Visits to a representative sample of gardens on vacant land confirmed that the Google Earth images were gardens producing food.

They found more than 4,600 urban agriculture sites equaling 65 acres of food production. Using Census data, they found that areas with large Chinese-origin populations had greater concentrations of gardens. Other gardening neighborhoods had large numbers of Polish and Eastern and Southern European immigrants.

Their research has been published in Landscape and Urban Planning.