Soil Research Soil Research Society
Soil, land care and environmental research

Characterisation and evaluation of biochars for their application as a soil amendment

Balwant Singh A D , Bhupinder Pal Singh B and Annette L. Cowie C

A Faculty of Agriculture, Food and Natural Resources, The University of Sydney, Sydney, NSW 2006, Australia.

B Forest Science Centre, Industry and Investment NSW, PO Box 100, Beecroft, NSW 2119, Australia.

C National Centre for Rural Greenhouse Gas Research, University of New England, Armidale, NSW 2351, Australia.

D Corresponding author. Email:

Australian Journal of Soil Research 48(7) 516-525
Submitted: 10 March 2010  Accepted: 24 May 2010   Published: 28 September 2010


Biochar properties can be significantly influenced by feedstock source and pyrolysis conditions; this warrants detailed characterisation of biochars for their application to improve soil fertility and sequester carbon. We characterised 11 biochars, made from 5 feedstocks [Eucalyptus saligna wood (at 400°C and 550°C both with and without steam activation); E. saligna leaves (at 400°C and 550°C with activation); papermill sludge (at 550°C with activation); poultry litter and cow manure (each at 400°C without activation and at 550°C with activation)] using standard or modified soil chemical procedures. Biochar pH values varied from near neutral to highly alkaline. In general, wood biochars had higher total C, lower ash content, lower total N, P, K, S, Ca, Mg, Al, Na, and Cu contents, and lower potential cation exchange capacity (CEC) and exchangeable cations than the manure-based biochars, and the leaf biochars were generally in-between. Papermill sludge biochar had the highest total and exchangeable Ca, CaCO3 equivalence, total Cu, and potential CEC, and the lowest total and exchangeable K. Water-soluble salts were higher in the manure-based biochars, followed by leaf, papermill sludge, and wood biochars. Total As, Cd, Pb, and polycyclic aromatic hydrocarbons in the biochars were either very low or below detection limits. In general, increase in pyrolysis temperature increased the ash content, pH, and surface basicity and decreased surface acidity. The activation treatment had a little effect on most of the biochar properties. X-ray diffraction analysis showed the presence of whewellite in E. saligna biochars produced at 400°C, and the whewellite was converted to calcite in biochars formed at 550°C. Papermill sludge biochar contained the largest amount of calcite. Water-soluble salts and calcite interfered with surface charge measurements and should be removed before the surface charge measurements of biochar. The biochars used in the study ranged from C-rich to nutrient-rich to lime-rich soil amendment, and these properties could be optimised through feedstock formulation and pyrolysis temperature for tailored soil application.

Additional keywords: carbon sequestration, soil fertility, pyrolysis, Boehm titrations, heavy metals, surface acidity.


Baldock JA Smernik RJ 2002 Chemical composition and bioavailability of thermally altered Pinus resinosa (Red pine) wood. Organic Geochemistry 33 1093 1109 doi:10.1016/S0146-6380(02)00062-1

Boehm HP 1994 Some aspects of the surface-chemistry of carbon-blacks and other carbons. Carbon 32 759 769 doi:10.1016/0008-6223(94)90031-0

Chan KY , Xu Z (2009) Biochar: nutrient properties and their enhancement. In ‘Biochar for environmental management: science and technology’. (Eds J Lehmann, S Joseph) pp. 67–84. (Earthscan: London)

Chan KY Van Zwieten L Meszaros IA Downie A Joseph S 2007 Agronomic values of greenwaste biochar as a soil amendment. Australian Journal of Soil Research 45 629 634 doi:10.1071/SR07109

Chan KY Van Zwieten L Meszaros IA Downie A Joseph S 2008 Using poultry litter biochars as soil amendments. Australian Journal of Soil Research 46 437 444 doi:10.1071/SR08036

Cheng C-H Lehmann J Engelhard MH 2008 Natural oxidation of black carbon in soils: changes in molecular form and surface charge along a climosequence. Geochimica et Cosmochimica Acta 72 1598 1610 doi:10.1016/j.gca.2008.01.010

Cheng C-H Lehmann J Thies JE Burton SD Engelhard MH 2006 Oxidation of black carbon by biotic and abiotic processes. Organic Geochemistry 37 1477 1488 doi:10.1016/j.orggeochem.2006.06.022

Chun Y Sheng G Chiou CT Xing B 2004 Compositions and sorptive properties of crop residue-derived chars. Environmental Science & Technology 38 4649 4655 doi:10.1021/es035034w

Contescu A Contescu C Putyera K Schwarz JA 1997 Surface acidity of carbons characterized by their continuous pK distribution and Boehm titration. Carbon 35 83 94 doi:10.1016/S0008-6223(96)00125-X

Contescu A Vass M Contescu C Putyera K Schwartz JA 1998 Acid buffering capacity of basic carbons revealed by their continuous pK distribution. Carbon 36 247 258 doi:10.1016/S0008-6223(97)00168-1

Gaskin JW Steiner C Harris K Das KC Bibens B 2008 Effect of low-temperature pyrolysis conditions on biochars for agricultural use. Transactions of the ASABE 51 2061 2069

Glaser B Haumaier L Guggenberger G Zech W 2001 The Terra Preta phenomenon: a model for sustainable agriculture in the humic tropics. Naturwissenschaften 88 37 41 doi:10.1007/s001140000193

Glaser B Lehmann J Zech W 2002 Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal – a review. Biology and Fertility of Soils 35 219 230 doi:10.1007/s00374-002-0466-4

Guo Y Rockstraw DA 2007 Activated carbons prepared from rice hull by one-step phosphoric acid activation. Microporous and Mesoporous Materials 100 12 19 doi:10.1016/j.micromeso.2006.10.006

Horne PA Williams PT 1996 Influence of temperature on the products from the flash pyrolysis of biomass. Fuel 75 1051 1059 doi:10.1016/0016-2361(96)00081-6

Knicker H 2007 How does fire affect the nature and stability of soil organic nitrogen and carbon? A review. Biogeochemistry 85 91 118 doi:10.1007/s10533-007-9104-4

Lal R 2009 Challenges and opportunities in soil organic matter research. European Journal of Soil Science 60 158 169 doi:10.1111/j.1365-2389.2008.01114.x

Lehmann J Gaunt J Rondon M 2006 Bio-char sequestration in terrestrial ecosystems – a review. Mitigation and Adaptation Strategies for Global Change 11 403 427 doi:10.1007/s11027-005-9006-5

Lehmann J Pereira da Silva J Steiner C Nehls T Zech W Glaser B 2003 Nutrient availability and leaching in an archaeological Anthrosol and a Ferralsol of the Central Amazon basin: fertilizer, manure and charcoal amendments. Plant and Soil 249 343 357 doi:10.1023/A:1022833116184

Liang B Lehmann J Solomon D Kinyangi J Grossman J O’Neill B Skjemstad JO Thies J Luizão FJ Peterson J Neves EG 2006 Black carbon increases cation exchange capacity in soils. Soil Science Society of America Journal 70 1719 1730 doi:10.2136/sssaj2005.0383

McBeath AV Smernik RJ 2009 Variation in the degree of aromatic condensation of chars. Organic Geochemistry 40 1161 1168 doi:10.1016/j.orggeochem.2009.09.006

Miller R (1998) Nitric-perchloric acid wet digestion in an open vessel. In ‘Handbook of reference methods for plant analysis’. (Ed. YP Kalra) pp. 57–61. (CRC Press: New York)

NEPM (1999) ‘National Environment Protection (Assessment of site contamination) Measure 1999.’ (National Environment Protection Council: Adelaide, S. Aust.)

Nguyen BT Lehmann J Hockaday WC Joseph S Masiello CA 2010 Temperature sensitivity of black carbon decomposition and oxidation. Environmental Science & Technology 44 3324 3331 doi:10.1021/es903016y

Novak JM Lima I Xing B Gaskin JW Steiner C Das KC Ahmedna M Rehrah D Watts DW Busscher WJ Schomberg H 2009 Characterization of designer biochar produced at different temperatures and their effects on a loamy sand. Annals of Environmental Science 3 195 206

Orians GH Milewski AV 2007 Ecology of Australia: the effects of nutrient-poor soils and intense fires. Biological Reviews of the Cambridge Philosophical Society 82 393 423 doi:10.1111/j.1469-185X.2007.00017.x

Payne RW , Murray DA , Harding SA , Baird DB , Soutar DM (2009) ‘Genstat for Windows.’ 12th edn. (VSN International: Hemel Hempstead, UK)

Rayment GE , Higginson FR (1992) ‘Australian laboratory handbook of soil and water chemical methods.’ (Inkata Press: Melbourne, Vic.)

Rodriguez-Navarro C Ruiz-Agudo E Luque A Rodriguez-Navarro AB Alejandro B Ortega-Huertas M 2009 Thermal decomposition of calcite: mechanisms of formation and textural evolution of CaO nanocrystals. American Mineralogist 94 578 593 doi:10.2138/am.2009.3021

Shinogi Y Yoshida H Koizumi T Yamaoka N Saito T 2003 Basic characteristics of low-temperature carbon products from waste sludge. Advances in Environmental Research 7 661 665 doi:10.1016/S1093-0191(02)00040-0

Singh BP , Cowie AL (2008) A novel approach, using 13C natural abundance, for measuring decomposition of biochars in soil. In ‘Carbon and Nutrient Management in Agriculture, Fertilizer and Lime Research Centre Workshop Proceedings’. Massey University, Palmerston North, New Zealand. Occasional Report No. 21. (Eds LD Currie, LJ Yates) (Massey University: New Zealand)

Singh BP Hatton BJ Singh B Cowie AL Kathuria A 2010 Influence of biochars on nitrous oxide emission and nitrogen leaching from two contrasting soils. Journal of Environmental Quality 39 1224 1235 doi:10.2134/jeq2009.0138

Sombroek WG (1966) Amazon soils. A reconnaissance of the soils of the Brazilian Amazon region. Versl Landbouwkd Onderz No. 672, p.292.

Steiner C Teixeira WG Lehmann G Nehls T de Macedo JLV Blum WEH Zech W 2007 Long-term effects of manure, charcoal and mineral fertilization on crop production and fertility on a highly weathered central Amazonian upland soil. Plant and Soil 291 275 290 doi:10.1007/s11104-007-9193-9

Stevenson FJ , Cole MA (1999) ‘Cycles of soil: carbon, nitrogen, phosphorus, sulfur and micronutrients.’ 2nd edn (John Wiley & Sons Inc.: New York)

Tsai WT Lee MK Chang YM 2006 Fast pyrolysis of rice straw, sugarcane bagasse and coconut shell in an induction–heating reactor. Journal of Analytical and Applied Pyrolysis 76 230 237 doi:10.1016/j.jaap.2005.11.007

Tyron EH 1948 Effect of charcoal on certain physical, chemical and biological properties of forest soils. Ecological Monographs 18 81 115 doi:10.2307/1948629

Van Zwieten L Kimber S Morris S Chan YK Downie A Rust J Joseph S Cowie A 2010 Effects of biochar from slow pyrolysis of papermill waste on agronomic performance and soil fertility. Plant and Soil 327 235 246 doi:10.1007/s11104-009-0050-x

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