The word ???polycultures??? describes farm systems that include a number of diverse crops growing together. A common example of a polyculture system is the ???three sisters???, a growing system that includes corn, beans, and squash growing together in the same spot. The corn plant grows quickly, providing support for vining bean plants. Squash plants have shallow roots and wide leaves that produce shade and limit competition from weeds. The roots of bean plants fix nitrogen in the soil, adding fertility and providing extra nitrogen that corn plants need so survive. All three of the plants provide a yield of food. They also provide complementary services to support each other.

Polycultures can also be used to describe the social movement that has formed around the support of local food systems, including the collaboration of diverse communities, both rural and urban, around the provision of local food.

Food is energy. Not much thought is given to it, but every time that we eat, our bodies convert food calories into a fuel that powers everything that we do, from typing at a computer, making art, walking or biking into town, fixing a house, or digging a garden bed.

Over the past 10,000 years, humans have developed agriculture -- the cultivation of land and active management of crops and animals to increase the food-calories available for growing human populations.