Soybean production has become a significant force for economic development in Brazil, but has come at the cost of expansion into non-protected forests in the Amazon and native savanna in the Cerrado. Over the past fifty years, production has increased from 26 million to 260 million tons. Area planted to soybeans has increased from roughly 1 million hectares in 1970 to more than 23 million hectares in 2010, second only to the United States.
For more than three decades, deforestation in the Amazon has been driven by the expansion of pasturelands for cattle production. Pasture area also expanded rapidly because soils found throughout much of the region are poor in nutrients following forest slash and burn, and crop production cannot be maintained in the face of degradation of soils and lost vegetation productivity. In the late 1990s, multi-national corporations such as Cargill began investing in infrastructure throughout the south-central Amazon. New river ports, fertilizer and mechanization have fueled explosive growth in the crop agricultural sector, especially for soybeans. For example, in the State of Mato Grosso, soybean agriculture has increased at a rate of 1,000 to 2,000 km2 per year since 2000, making it the fastest growing form of land use regionally. Much of this deforestation is now being driven directly by conversion to soybean fields, the soy oil and meal from which are being used largely by the growing industrial livestock sector in Brazil, China, India, and other countries around the world.
In the same period that soy agriculture has boomed in the Brazilian Amazon, the power of satellite monitoring technology has also gone through a revolution. Since 2000, it has been possible to monitor not only rates of deforestation on a weekly basis (it was done annually prior to 2000), but also to differentiate between forest areas cleared for cattle pasture or crop agriculture. In addition, selective timber harvests of intact forests - a geographic precursor to deforestation - can now be monitored annually. Using the NASA Terra, Landsat 7 and Earth Observing-1 satellite sensors, it is now possible to measure the location and extent of pasture, cropland and timber harvesting across the entire Amazon. These measurements are vital to understanding not only the dynamics of land-use change in a large and poorly regulated region of Brazil, but also the impacts of these changes on ecosystem function. We will use seed funds from this project grant to advance the satellite-based measurements of soybean expansion in the Amazon.
While these satellite-based measurements can now tell us the extent and rate of change, we also require on-the-ground measurements to evaluate the consequences of these changes. There has been substantial research on the biogeochemical and climatic consequences of forest conversion to pasture in Amazonia, but less ecosystem-level research on the now-dominant soybean system and its consequences. These consequences are likely to include changes in soils and soil fertility, fluxes of trace gases that function as greenhouse gases or as precursors to photochemical smog, and runoff of nutrients and sediments to aquatic systems. In addition, the energy requirements of the intensive agricultural system can themselves drive deforestation for fuel - and the nutrients mobilized in agricultural products move in international trade and can cause water and air pollution where they are used. We will work with Professor Luiz Martinelli (University of Sao Paulo) and his students to begin the development of integrated nutrient budgets for the forest to soybean conversion, and its ancillary effects.