title: Kinetics of carbon mineralization of biochars compared with wheat straw in three soils.
abstract: Application of biochars to soils may stabilize soil organic matter and sequester carbon (C). The objectives of our research were to study in vitro C mineralization kinetics of various biochars in comparison with wheat straw in three soils and to study their contribution to C stabilization. Three soils (Oxisol, Alfisol topsoil, and Alfisol subsoil) were incubated at 25°C with wheat straw, charcoal, hydrothermal carbonization coal (HTC), low-temperature conversion coal (LTC), and a control (natural organic matter). Carbon mineralization was analyzed by alkali absorption of CO released at regular intervals over 365 d. Soil samples taken after 5 and 365 d of incubation were analyzed for soluble organic C and inorganic N. Chemical characterization of biochars and straw for C and N bonds was performed with Fourier transformation spectroscopy and with the N fractionation method, respectively. The LTC treatment contained more N in the heterocyclic-bound N fraction as compared with the biochars and straw. Charcoal was highly carbonized when compared with the HTC and LTC. The results show higher C mineralization and a lower half-life of straw-C compared with biochars. Among biochars, HTC showed some C mineralization when compared with charcoal and LTC over 365 d. Carbon mineralization rates were different in the three soils. The half-life of charcoal-C was higher in the Oxisol than in the Alfisol topsoil and subsoil, possibly due to high Fe-oxides in the Oxisol. The LTC-C had a higher half-life, possibly due to N unavailability. We conclude that biochar stabilization can be influenced by soil type.
authors: Justus Liebig University, Giessen, Germany. farooq.qayyum@ernaehrung.uni-giessen.de
authors: Muhammad Farooq
authors: MF
authors: Qayyum
authors: Diedrich
authors: D
authors: Steffens
authors: Hans Peter
authors: HP
authors: Reisenauer
authors: Sven
authors: S
authors: Schubert
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D007700:Kinetics; D009584:Nitrogen / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D014908:Triticum / Q000737:chemistry*
chemical_list: D012987:Soil; C540010:biochar; D002606:Charcoal; D002244:Carbon; D009584:Nitrogen