Talk of ecological diversity or saving rare species does not fly very far in Mato Grosso. The state is Brazil's top soy producer, churning out an annual harvest of about 18 million tones. Fields of emerald green line the highways, stretching out to horizons so flat they look drawn with a ruler. The crops have helped fuel Brazil's economic boom of recent years but they come at a price -- the clearing of more than 130,000 square km (50,000 square miles) of Amazon rain forest in the state from 1988 through 2008, to the widespread condemnation of environmental groups. Years of acrimony have built up. When a visitor mentions environmentalists, the faces of Mato Grosso farmers often cloud with hostility. So, with "save the world" emotional appeals not working, environmentalists are turning to economic arguments, stressing how preserving the world's largest forest can mean bigger profits for farmers.