From Science Daily: Brazil is exporting more and more agricultural produce: soya beans and beef in particular, but also corn, rice and sugar. Taken together, these exports represent half of Brazil’s total today. The increase in the export of commodities brings both a higher degree of economic dependency and a threat to the Amazon rainforest, as outlined by an IRD geographer and his Brazilian counterparts (1). Agricultural produce is actually the cause of almost all deforestation in Brazil, where 750,000 km² of forest have disappeared — and 80% of that was converted into grazing land for cattle. Recently, the increase of single-crop farming, especially of soya beans, has pushed herds further and further into forested areas, and so accelerated the process of deforestation.
http://www.sciencedaily.com/releases/2012/02/120228123849.htm