University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Master / Diploma Thesis:
Maria Rechberger
(2015):
Changes of Biochar Characteristics during Aging in Soils.
Master / Diploma Thesis - Institut für Bodenforschung (IBF),
BOKU-Universität für Bodenkultur,
pp 42.
UB BOKU
obvsg
- Abstract:
- Biochar (BC) is a porous aromatic solid product that is obtained by pyrolysis of biogenic material and used as soil amendment or for carbon sequestration in soils. In this study, changes of BC characteristics during incubation in soil were investigated. To this end, biochars from two different feedstocks, willow wood (Salix alba) and wheat husks (Triticum aestivum), were produced at two different highest treatment temperatures: Willow wood at 400°C and 525°C and wheat husks at 525°C (S525). The BCs were incubated at two different temperatures (20°C and 30°C) for 0, 6 and 24 months in two contrasting soils: an acidic Planosol and a calcareous Chernozem. BC-soil mixtures were analysed regarding pH, dissolved organic carbon (DOC), nitrate and ammonium. Scanning environment microscopy of isolated BC pieces displayed no visible change of surface structure due to incubation. Contact angle measurement of BC pieces revealed that the surfaces of freshly produced willow BCs were highly hydrophobic but became hydrophilic within 2 years of incubation. Attenuated total reflectance mid-infrared (MIR) spectroscopy showed that the BCs' molecular characteristics changed due to aging processes. Furthermore, there was an overall increase in bands assigned to H- and O-containing functional groups within 24 months of incubation. This indicates oxidation processes and accordingly formation of acidic functional groups which feature hydrophilic properties. Incubation in the acidic Planosol led to accelerated and stronger changes of BC molecular properties and stronger increase in hydrophilic properties compared to incubation in the calcareous Chernozem. The results indicate that if BCs are applied to soil without pretreatment it can take months to years until BC particles develop hydrophilic properties enabling interaction with the soil solution and hence providing beneficial properties such as improved nutrient and water holding capacity.
- Beurteilende(r): Zehetner Franz
- 1.Mitwirkender: Müller Stefanie