Nitrogen budget in South America: observation and modeling

Jean Pierre Ometto1; Nnet Project team2

1National Institute for Space Research (INPE)

Av dos Astronautas, 1758

12227-010 – São José dos Campos, SP, Brazil



This paper, mirrored in the project report, presents a regional initiative, in South America, which aims to synthesize scientific information, acquire new data and informing the policy processes on the nitrogen budget and nutrient management in a broad region. The goal of this network is to examine human impact in natural and modified ecosystems across a wide range of climates, and ranging from direct measurements to regional modeling.  The up-scaling of local nitrogen studies aims to constrain regional atmospheric chemistry and transport modeling, feeding global models, greatly enhancing our understanding of global patterns of alterations to the nitrogen cycle. In the study sites, defined according to physiographic and/or socio-economic attributes, the following inputs and outputs of nitrogen are being reviewed and analyzed: (i) Inputs: Natural-BNF and cultivation induced-BNF, fertilizer use, atmospheric deposition;  (ii) Outputs: Net exports of agricultural products at regional level and estimates at site scale of gaseous emissions from land use (fertilizer volatilization, biogenic soil emissions and burning) and export of N to groundwater and surface waste (domestic, agricultural and industrial).