Pedosphere 27(5): 822--831, 2017
ISSN 1002-0160/CN 32-1315/P
©2017 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Can biochar protect labile organic matter against mineralization in soil?
Giovanna B. MELAS1,2,3, Oriol ORTIZ4, Josep M. ALACAÑIZ1,2
1Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia, Facultat de Biociències, Universitat Autònoma de Barcelona, Cerdanyola del Vallès 08193 (Spain)
2Centre de Recerca Ecologica i Aplicacions Forestals (CREAF), Cerdanyola del Vallès E08193 (Spain)
3Dipartimento di Agraria, Universitá degli Studi di Sassari, Viale Italia 39, Sassari 07100 (Italia)
4Departamento de Ciencias Agrarias y del Medio Natural, Escuela Politécnica Superior de Huesca, Universidad de Zaragoza, Huesca E22071 (Spain)
Corresponding Author:Giovanna B. MELAS
ABSTRACT
      Biochar could help to stabilize soil organic (SOM) matter, thus sequestering carbon (C) into the soil. The aim of this work was to determine an easy method i) to estimate the effects of the addition of biochar and nutrients on the organic matter (SOM) mineralization in an artificial soil, proposed by the Organization for Economic Co-operation and Development (OECD), amended with glucose and ii) to measure the amount of labile organic matter (glucose) that can be sorbed and thus be partially protected in the same soil, amended or not amended with biochar. A factorial experiment was designed to check the effects of three single factors (biochar, nutrients, and glucose) and their interactions on whole SOM mineralization. Soil samples were inoculated with a microbial inoculum and preincubated to ensure that their biological activities were not limited by a small amount of microbial biomass, and then they were incubated in the dark at 21℃ for 619 d. Periodical measurements of C mineralized to carbon dioxide (CO2) were carried out throughout the 619-d incubation to allow the mineralization of both active and slow organic matter pools. The amount of sorbed glucose was calculated as the difference between the total and remaining amounts of glucose added in a soil extract. Two different models, the Freundlich and Langmuir models, were selected to assess the equilibrium isotherms of glucose sorption. The CO2-C release strongly depended on the presence of nutrients only when no biochar was added to the soil. The mineralization of organic matter in the soil amended with both biochar and glucose was equal to the sum of the mineralization of the two C sources separately. Furthermore, a significant amount of glucose can be sorbed on the biochar-amended soil, suggesting the involvement of physico-chemical mechanisms in labile organic matter protection.
Key Words:  C source, glucose sorption, microbial biomass, nutrients, soil respiration
Citation: Melas, B., Oriol, O. and AlacaÑiz, M. 2017. Can biochar protect labile organic matter against mineralization in soil?. Pedosphere. 27(5): 822-831.
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