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Journal of Environmental Quality Abstract - Special Section: Environmental Benefits of Biochar

Kinetics of Carbon Mineralization of Biochars Compared with Wheat Straw in Three Soils


This article in JEQ

  1. Vol. 41 No. 4, p. 1210-1220
    Received: Feb 22, 2011

    * Corresponding author(s): farooq.qayyum@ernaehrung.uni-giessen.de
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  1. Muhammad Farooq Qayyum *a,
  2. Diedrich Steffensa,
  3. Hans Peter Reisenauerb and
  4. Sven Schuberta
  1. a Institute of Plant Nutrition, Research Center for BioSystems, Land Use and Nutrition, Justus Liebig Univ., Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany
    b Institute of Organic Chemistry, Justus Liebig Univ., Heinrich-Buff-Ring 58. 35392 Giessen, Germany. Assigned to Associate Editor David Laird


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 CO2 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.

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