Molecular characterization of soil organic matter from native vegetation-pasture-sugarcane transitions in Brazil

Author(s)

da Silva Oliveira, Dener Marcio ^{[1, 2]} ; Schellekens, Judith ^[1] ; Pellegrino Cerri, Carlos Eduardo ^[1]

Affiliation

^[1] Univ Sao Paulo, Luiz de Queiroz Coll Agr, Dept Soil Sci, 11 Paduas Dias Ave, BR-13418900 Piracicaba, SP - Brazil

^[2] Colorado State Univ, Nat Resource Ecol Lab, 1231 East Dr, Ft Collins, CO 80523 - USA

• Document type: Journal article
• Source: Science of The Total Environment; v. 548, p. 450-462, APR 1 2016.
• Web of Science Citations: 10

Abstract

Replacing pastures (PA) with sugarcane (SG) has been deemed an agronomically feasible strategy for sugarcane expansion in Brazil. However, there are some uncertainties about the environmental impacts regarding this land use change (LUC), mainly related to soil organic matter (SOM), a key factor of environmental sustainability of Brazilian ethanol. LUC-related losses of SOM can overcome the C savings from biofuels. The molecular composition of SOM was evaluated to understand the C dynamics regarding LUC from PA to SG, using native vegetation (NV) as reference. Our study area was located in the south-central region of Brazil. Soil sampling was performed at three depths (0-0.1 m, 0.2-0.3 m and 0.9-1 m) in three representative sites with known LUC history and management practice since 1970. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was chosen to study SOM chemistry. Content and isotopic composition of soil organic C and N were also determined. The LUC caused decreases on C and N contents and on delta C-13 isotopic values. Depth was the major factor that influenced SOM composition, while the influence of LUC was mainly evident in surface soils and diminished rapidly with depth. The main difference in SOM composition undergoing the conversion PA-SG was a higher contribution from compounds associated to fresh litter inputs. The high contribution from fresh litter, having a relatively low mean residence time and increasing decomposition rates, is probably a major factor that drives C losses in areas undergoing sugarcane expansion. (C) 2016 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 13/03953-9 - Organic matter dynamics in tropical peatlands (Diamantina, Brasil) - development of molecular proxies to reconstruct environmental changes
• Grantee: Judith Schellekens
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/14122-6 - Estimating soil carbon changes regarding sugarcane expansion into pastures in Brazil
• Grantee: Dener Márcio da Silva Oliveira
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 14/08632-9 - Soil organic matter in land use change areas under sugarcane cultivation in south central region of Brazil
• Grantee: Dener Márcio da Silva Oliveira
• Support Opportunities: Scholarships in Brazil - Doctorate