Ducks swim in canal near Mai Chau

Ducks not only provide food for farmers but also weed the rice fields and fertilize the rice with their droppings. (Photograph by Margery H. Freeman. More about the photograph)

In many parts of Southeast Asia, farmers raise ducks and farm wet-rice fields in a mutually beneficial, or symbiotic, relationship. Duck droppings fertilize the water in which the rice grows. Ducks also eat the algae and other weeds that grow near the young rice plants. The ducks are herded away from the ripe rice when it is ready for harvest. The farmers ultimately eat both the mature rice and ducks.

The ducks shown here swimming in a canal near Mai Chau are a domesticated breed raised by highland rice farmers.