|Grado Académico||Doctor en Ciencias en Recursos Naturales|
|Facultad / Universidad||Facultad de Ciencias Agrarias. Universidad Austral de Chile|
|Adscipción Actual||Postoctorado Universidad Austral de Chile|
|Profesor Patrocinante||José Dörner|
|Profesores – Comisión|
|Línea de Investigación CISVo||Calidad y Funcionamiento de Suelos Volcánicos|
Postdoctoral Research Abstract
Title: The influence of physical and chemical properties in Ñadi soils under different land uses on the structure and function of Nitrogen-transforming bacterial communities
Microorganisms, in the course of their growth and metabolism, interact successively in re-cycling of nutrients such as Nitrogen (N). Nitrogen is an element essential for life and takes different forms in soil, corresponding to different oxidation states. The two main transformations of N mediated by soil microbes are nitrification and denitrification. These processes result in N2O emission, an important greenhouse gas (GHG). Moreover, the conditions for nitrification and denitrification to take place in agricultural soils are related at different factors such as availability of substrates (N fertilizers), suitable aerobic and anaerobic conditions, optimum soil pH, and temperature.
Ñadi soils (Aquands) are located in southern Chile (38°30’–43°00’ S) and are dominated by grasslands that support the major livestock production and, consequently, one of the most relevant grassland agro-ecosystems in Chile. Moreover, these soils present extreme and contrasting water content conditions depending on the water table height. The waterlogged conditions of these soils increases the presence of anaerobic bacteria (e.g. denitrifying bacteria). Soil temperature may also play an important role due to changing temperature diffusion as a function of water saturation degree. Thus, understanding soil factors and possible differences in the diversity and function of N-transforming bacterial communities could help explain the nitrification and denitrification rates and N2O production in Ñadi soils. Which are also relevant considering the potential consequences of increase in soil temperature and reduction in rainfalls southern Chile (climate change).
The general objective of this research is to assess the effect of land use change of the Ñadi soils (under secondary native forest and grassland) on their physical and chemical properties in order to identify which factors are driving the composition and function of N-transforming bacterial communities (specifically, denitrifying and nitrifying bacterial communities). The specific goals of this study are: 1) to investigate the composition, abundance and gene expression of N-transforming bacteria communities in Ñadi soils, 2) to evaluate the effects water-filled porosity and N fertilization in Ñadi soil on the composition and abundance of N-transforming bacteria communities under soil incubations conditions and 3) to determine the relationship between nitrification and denitrification potential enzyme activities and gene expression of N-transforming bacteria communities under soil incubations conditions. To carry out these objectives, I will work with the Dr. José Dörner research group at the Universidad Austral de Chile, where we will use a chemical and physical measures in analyzing the Ñadi soils properties and molecular techniques approaches (DGGE and qPCR) for analyzing of composition, abundance and expression of N-transforming bacterial genes (16S rDNA, amoA, nirS, nirK, nosZ).
Keywords: Ñadi soils – physical and chemical soil properties – water-filled porosity – N fertilization – Nitrogen-transforming bacterial communities