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Kinetics of Carbon Mineralization of Biochars Compared with Wheat Straw in Three Soils
Author(s) -
Qayyum Muhammad Farooq,
Steffens Diedrich,
Reisenauer Hans Peter,
Schubert Sven
Publication year - 2012
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2011.0058
Subject(s) - alfisol , mineralization (soil science) , biochar , oxisol , chemistry , soil water , topsoil , charcoal , straw , subsoil , soil carbon , environmental chemistry , agronomy , pyrolysis , soil science , environmental science , nitrogen , organic chemistry , inorganic chemistry , biology
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 2 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.