Agriculture in the Neotropics and ecosystem changes to the N cycle
Results/Conclusions The use of N-fertilizer in the most areas of the Neotropics had an unprecedent increase in the last decades. Taking Latin America that most of its area is in the subtropical and tropical areas of the Neotropics as an example, in the beginning of the 60xs only 5 kg N ha-1 of N-fertilizer was used over an area of arable land equivalent to 7% of the world's arable lands. Sixty years later, the use of N-fertilizer increased to 45 kg N ha-1 and the arable land increased to 12% of the total world's arable lands. Therefore, the N-rich ecosystems of the Neotropics are receiving an increasing amount of N without a thorough evaluation of its consequences. At the same time, in these sixty years urbanization rate had one of the most intense growths in the world, increasing to approximately 90% in the 2000xs. Most of the cities in the Neotropics do not treat domestic sewage, as a consequence rivers and estuary receive enormous amount of N with a series of consequences to the water chemistry and biodiversity. Such consequences will be discussed in our presentation.