This is a summary of the most salient project results. For further information see the project website, project papers or contact the investigators directly.
The aim of the project is to provide an understanding of the Continent’s N cycle. Biological Nitrogen Fixation (BNF) is estimated by compiling data from published, and not yet published information on natural and anthropogenic systems. The information is only being prepared, including a literature review of N dynamics in several tropical ecosystems. The results may be refined with field data being collected in several regions.
Measured ∂15-N abundance in Mexico indicated 30-50% of N in native plants is biologically fixed. The standing vegetation contained 70-100 kg N /ha with a turnover (litter fall) of 20-30 kg N /ha/yr. These figures will yet have to be scaled and related to environmental conditions to be useful for a continental picture.
In Chilean forests, measured (by acetylene reduction) BNF was extremely low and further reduced by contaminants from copper mining which poison the N cycle. In a laboratory study on factors limiting BNF, the only statistically significant result is seen with Mo. The entire cycle of BNF, mineralization (buried bags), denitrification (acetylene inhibition) and litter fall is yet to be integrated.
The expansion of soy production is being analyzed in Bolivia for the potential future impacts of increased fertilizer use, soil degradation and water contamination. This includes analysis of the water footprint of the crop. In addition, a chronosequence of slash-burn agriculture has been sampled.
Nitrogen deposition has been measured and the first maps produced for Brazil and Northern Argentina. Deposition in Argentina is near 8 kg N /ha/y. First Maps of air contaminants for São Paulo State show the overwhelming effect of the city and adjacent industrial areas with high NOx concentrations, and contributions to NH3 from rural animal production sites. A European Air Pollution Dispersion–Chemical Transport Model is being initialized with known N source data for Brazil to provide a synthesis tool for these data.
Re-analysis of IVIC’s repository of Venezuelan river N data show polluted rivers with 60x background concentrations (Amazon, Orinoco).
All these pieces still need to be assembled into regional understanding.
Director: Amy Austin
IFEVA-Facultad de Agronomía- UBA
El proyecto CONICET-IAI 3005 se propone reunir a expertos argentinos y expertos extranjeros en un ejercicio de síntesis, capacitación y exploración sobre el ciclo del nitrógeno en áreas cultivadas (fertilizadas y no) y no cultivadas de los pastizales pampeanos, los impactos de los cambios en el uso del suelo en los aportes de nitrógeno y su redistribución, y las posibles estrategias de mitigación y adaptación. Se espera evaluar escenarios de uso del nitrógeno en agricultura mediante análisis costo-beneficio efectuados desde los puntos de vista privado y social, considerando beneficios financieros, externalidades y servicios ambientales. El proceso prevé una primera etapa de síntesis de datos y dos talleres incluyendo ejercicios de síntesis y exploración de impactos socio-ecológicos mediante modelaje.
Jean Pierre H.B. Ometto (firstname.lastname@example.org)
Maria Cristina Forti (email@example.com)
Cecilia Pérez (firstname.lastname@example.org)
Universidad de Chile, Chile
Ariel Stein (email@example.com)
Earth Res. and Tech. On assignment to NOAA’s Air Resources Laboratory, USA
Víctor J. Jaramillo (firstname.lastname@example.org)
Universidad Nacional Autónoma de México (UNAM), Mexico
Tibisay Perez (email@example.com)
Instituto Venezolano de Investigaciones Cientificas (IVIC), Venezuela
Amy Austin (firstname.lastname@example.org)
Universidad de Buenos Aires and IFEVA, Argentina
Nataly Ascarrunz (email@example.com)
Instituto Boliviano de Investigación Forestal (IBIF), Bolivia
Patricia Pinho (firstname.lastname@example.org)
Universidade de São Paulo (USP), Brazil
Ana Lidia Sandoval Pérez, other, CINVESTAV- Instituto Politécnico Nacional, Mexico
Andre Bonilla, Undergraduate, Universidad Central de Venezuela, Venezuela
Beatriz Salgado, PHD, CATIE, Colombia
Cássia Monalisa dos Santos Silva, PHD, University of Cologne, Brazil
Conrado Guzmán Flores, Master, CINVESTAV- Instituto Politécnico Nacional, Mexico
Danilo Carnelos, PHD, Universidad de Buenos Aires, Argentina
Edixon Salazar, Undergraduate, Instituto Universitario de Tecnologia Región Capital, Venezuela
Eráclito Sousa Neto, Post Doctorate, Instituto Nacional de Pesquisas Espaciais, Brazil
Estefany Chávez Ibarra, Undergraduate, Universidad Michoacana de San Nicolás de Hidalgo, Mexico
Felipe Siqueira Pacheco, Post Doctorate, INPE, Brazil
Juan Carlos Licona, Master, Instituto Boliviano de Investigación Forestal, Bolivia
Kelly Ribeiro, PHD, INPE, Brazil
Laura Castañeda Gómez, Undergraduate, Pontificia Universidad Javeriana, Colombia
Luciene Gomes, PHD, INPE, Brazil
Marcio Malfaia, PHD, INPE, Brazil
Mariana Almeida, Master, INPE, Brazil
Natalia Muñoz, Master, Universidad de Los Andes, Colombia
Nohelis Hernandez, Undergraduate, IVIC, Venezuela
Raphael Dulhoste, Master, International Commission on Atmospheric Electricity, Francia
Rodrigo Aguilera Bazaes, Master, Universidad de Valparaiso, Chile
Stephane Palma Crispin, Undergraduate, INPE, Brazil
Stephanie Diaz, Master, IVIC, Venezuela
Nitrogen is a key element for life on Earth, related to ecosystem functioning and many human activities, and thus under strong pressure due to current global environmental changes. The lack of information on the nitrogen cycle in Latin America is a serious impediment to evaluate and project how human activity is altering nitrogen pools and turnover at regional and global scales. Empirical measurements of N deposition or processes are scarce and data lack spatial distribution information. This project is developing a Nitrogen Human Environment Network (Nnet) to examine human impact on natural and modified ecosystems across a wide range of climates. Direct measurements and regional modeling contribute to a greater understanding of how nitrogen excess or shortage affects ecosystem processes and biodiversity.
The project reviews across several study sites distributed along regional precipitation gradients, and defined according to physiographic and socio-economic attributes, the following inputs: Natural-BNF (biological nitrogen fixation) and cultivation induced-BNF, fertilizer use, atmospheric deposition; and 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), export of N to groundwater and surface waste (domestic, agricultural and industrial). Local information is scaled up by modeling regional-level nitrogen atmospheric deposition, atmospheric chemistry and transport. The regional modeling feeds to global models, enhancing understanding of global patterns of alterations to the nitrogen cycle.
The social and economical aspect is examined through drivers of LUC and N use at local and regional levels, analyzing the domestic and international forcing of those drivers (e.g., bioenergy, beef, soy production). To this end, a Group of Experts was created, composed of stakeholders from different sectors of society with expertise at the local and global levels.
The main goal is to have an integrated view of N management in the environment and of its essential role in sustaining life and minimizing its environmental degradation for Latin America. The network (1) disseminates knowledge on the causes and consequences of change in regional N cycle, and what are the implications on the ecosystems and people in the region. (2) Establishes guidelines for policymakers and the general public to make decisions regarding N management based on the integrated knowledge.