The expansion of soybeans into the Brazilian Amazon Basin is one of the most important land use changes taking place on earth. This project examines how soybean cultivation alters the runoff and chemistry of water reaching streams in small watersheds and how runoff from soy-bean fields differs from that of the forests and pastures that the soybeans replaced. Comparisons among streams of different sizes from forests, pastures and soybean fields will enable determina-tion of how stream size and the structure of riparian (stream-side) zones influence runoff pat-terns, water quantity and quality, and the locations in watersheds where major chemical trans-formations take place (or hotspots). Computer models will use the chemistry of water flowing through the soil and results of studies using chemical tracers to identify flow paths. This informa-tion will enable the contributions of runoff sources to stream flow and stream water chemistry to be determined. Results will be used to examine how soybean expansion will influence Amazon fresh waters over larger areas.
This project has high potential to influence land use decisions at the Amazon frontier be-cause research will be conducted on land farmed by the consortium that controls most of the soy-bean production and transport in the Brazilian Amazon. This consortium aims to reduce envi-ronmental consequences of soybean production in order to gain access to European markets. The field site will be used to develop a Brown University field course and to train Brazilian, U.S. and German graduate and undergraduate students.
