Disentangling organic carbon sequestration mechanisms of Brazilian Cerrados soils under different agricultural management with NanoSIMS

Abstract

Agricultural soils currently face challenges with population growth and climate change. Soils can have great potential for organic carbon (SOC) storage from the input of plant and animal residues, which can mitigate GHG emissions. Majority of tropical soils are known for their low fertility, occasioned mainly by low cation exchange capacity and acidity due to mineralogy. Appropriate soil management may mitigate these limitations and sustain production. The Cerrado region provides a unique opportunity to better understand soil carbon sequestration in tropical soils as determined by the intensification of agricultural production and restoration efforts of degraded soils. Preliminary results showed that intensified production systems with control of the animal stocking rate, use of lime and fertilizers can increase the SOC content compared to soils under an unmanaged system or native vegetation. The storage of SOC accumulation is probably related to interactions with highly abundant Fe and Al hydroxides in these soils. An advanced mechanistic understanding of the processes underlying the persistence of SOC is needed to predict the susceptibility and the role of management for increasing the SOC storage in Cerrados soils. This project will take advantage of a long-term field experiment by EMBRAPA for further analyses by physical fractionation to quantify particulate and mineral-associated SOC and characterize the bulk SOC using NMR. We aim to use nanoscale secondary ion mass spectrometry (nanoSIMS) to determine the spatial arrangement of usually patchy-distributed SOC and minerals at the submicron resolution. This will be the pioneer research project from Brazil using nanoSIMS to understand SOC storage. These aims will be enabled by exchange with Prof. Dr. Ingrid Kögel-Knaber (Chair of Soil Science, TUM Munich, Germany) who has internationally recognized experience in organo-mineral associations as mechanism of SOC storage. Altogether this proposal will foster the scientific exchange of cutting-edge techniques, enhance the international profile of the applicant and contribute to disentangle the storage of SOC in the Cerrado soils under different management. (AU)