Determining chemical composition of pyrogenic carbon in soil aggregates of Amazonian dark Earths

• Grant number: 13/21325-5
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Effective date (Start): January 10, 2014
• Effective date (End): September 30, 2014
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Alvaro Pires da Silva
• Grantee: Sâmala Glícia Carneiro Silva
• Supervisor: William Richard Horwath
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Research place: University of California, Davis (UC Davis), United States
• Associated to the scholarship: 12/06542-7 - PHYSICAL-HYDRIC AND STRUCTURAL CHARACTERIZATION OF SOILS WITH ANTHROPIC HORIZONS IN CAXIUANÃ/PA, BP.DR

Abstract

Soil organic matter of Amazonian Dark Earths (ADEs) is largely comprised of carbon of pyrogenic origin (PyC). Although it is well known that PyC represents a key constituent of these soils, exerting many important functions that enhance nutrient availability and organic matter stability, it is still unclear how PyC influence soil physical properties. Moreover, both a generally accepted definition of PyC composition and standard analytical procedures for the integrated analysis of different chemical and physical ADE fractions are lacking. The aim of this study is to quantify the distribution of pyrogenic carbon in physically protected (occluded) aggregate soil fractions, characterize its chemical composition, determine its impacts on soil aggregation patterns, as well as analyze the stability of different organic carbon fractions in ADEs. Fractionation of water stable aggregates and density fractionation of soil will be performed in conjunction with BPCA method using high performance liquid chromatography (HPLC). The BPCA approach will be combined with d13C measurements, using high-performance liquid chromatography-isotope-ratio mass spectrometry (HPLC-IRMS). (AU)