John, thanks for your question. For centuries, sugarcane fields have been burned to remove sugarcane straw (the plant’s tops and leaves), drive away snakes and other potentially poisonous animals, and make it easier for workers to cut the cane by hand.
However, technological advances and environmental concerns about local air pollution have increased demand for mechanized harvesting and the elimination of field burning. Over the last seven years, producers from Brazil´s Centre-South have invested around $4.5 billion in equipment purchases to increase mechanized harvesting of sugarcane. Mechanization already accounts for more than 70 percent of the harvest in São Paulo, Brazil’s top cane-producing state, and that proportion will grow to approximately 90 percent by 2014. Furthermore, a federal decree prohibits pre-harvest field burning as of 2018 on large farms that can be mechanized. In the meantime, sugarcane producers in Brazil must obtain an authorization from the State government each time they intend to burn sugarcane fields.
You can find more information on our website at http://sugarcane.org/sustainability/best-practices.