The effect of rice-husk char (potentially biochar) application on the growth of transplanted lettuce ( Lactuca sativa) and Chinese cabbage ( Brassica chinensis) was assessed in a pot experiment over a three crop (lettuce-cabbage-lettuce) cycle in Cambodia. The biochar was the by-product of a rice-husk gasification unit and consisted of 28.7% carbon (C) by mass. Biochar application rates to potting medium of 25, 50 and 150 g kg ？1 were used with and without locally available fertilizers (a mixture of compost, liquid compost and lake sediment). The rice-husk biochar used was slightly alkaline (pH 7.79), increased the pH of the soil, and contained elevated levels of some trace metals and exchangeable cations (K, Ca and Mg) in comparison to the soil. The biochar treatments were found to increase the final biomass, root biomass, plant height and number of leaves in all the cropping cycles in comparison to no biochar treatments. The greatest biomass increase due to biochar additions (903%) was found in the soils without fertilization, rather than fertilized soils (483% with the same biochar application as in the “without fertilization” case). Over the cropping cycles the impact was reduced; a 363% increase in biomass was observed in the third lettuce cycle.
References
[1]
Shackley, S.; Carter, S.; Knowles, T.; Middelink, E.; Haefele, S.; Sohi, S.; Cross, A.; Haszeldine, S. Sustainable gasification-biochar systems? A case study of rice-husk gasification in Cambodia Part I: Context, chemical properties, environmental and health and safety issues. Energy Policy 2012, 42, 49–58.
[2]
Shackley, S.; Carter, S.; Sims, K.; Sohi, S. Expert perceptions of the role of biochar as a carbon abatement option with ancillary agronomic and soil-related benefits. Energy Environ. 2010, 22, 167–187.
[3]
Shackley, S.; Carter, S.; Knowles, T.; Middelink, E.; Haefele, S.; Haszeldine, S. Sustainable gasification-biochar systems? A case-study of rice-husk gasification in Cambodia, Part II: Field trial results, carbon abatement, economic assessment and conclusions. Energy Policy 2012, 41, 618–623, doi:10.1016/j.enpol.2011.11.023.
[4]
Sokchea, H.; Borin, K.; Preston, T. Effect of biochar from rice husks (combusted in a downdraft gasifier or a paddy rice dryer) on production of rice fertilized with biodigester effluent or urea. Livest. Res. Rural Dev. 2013, 25. Article No. 4. Available online: http://www.lrrd.org/lrrd25/1/ sokc25004.htm (accessed on 23 January 2013).
[5]
Lehmann, J.; Gaunt, J.; Rondon, M. Bio-char sequestration in terrestrial ecosystems—A review. Mitig. Adapt. Strategies Glob. Chang. 2006, 11, 403–427.
[6]
Asai, H.; Samson, B.K.; Haefele, S.M.; Songyikhangs, K.; Homma, K.; Kiyono, Y.; Inoue, Y.; Shiraiwa, T.; Horie, T. Biochar amendment techniques for upland rice production in Northern Laos. 1. Soil physical properties, leaf SPAD and grain yield. Field Crops Res. 2009, 111, 81–84.
[7]
Hammond, J.; Shackley, S.; Prendergast-Miller, M.; Cook, J.; Buckingham, S.; Pappa, V. Biochar Field Testing in the UK: Outcomes and Implications for Use. Carbon Manag. 2013. in press.
[8]
Rice Production in Cambodia; Nesbitt, H.J., Ed.; International Rice Research Institute: Manilla, Philippines, 1997; pp. 15–29.
[9]
Shackley, S.; Sohi, S.P. An Assessment of the Benefits and Issues Associated with the Application of Biochar to Soil; Report to the Department for Environment, Food and Rural Affairs and the Department of Energy and Climate Change: London, UK, 2010; pp. 14–132.
[10]
International Biochar Initiative (IBI), Standardized Product Definition and Product Testing Guidelines for Biochar that is Used in Soil, International Biochar Initiative 2012. Available online: http://www.biochar-international.org/sites/default/files/guidelines_for_biochar_that_is_used_in_ soil_final.pdf (accessed on 21 January 2013).
[11]
European Biochar Certificate (EBC) Guidelines for a Sustainable Production of Biochar. Version 4.5; Delinat Institut and Biochar Science Network: Ayent, Switzerland, 2013. Available online: http://www.european-biochar.org/biochar/media/doc/1358641517626.pdf (accessed on 21 January 2013).
[12]
Sohi, S.P. Appendix 1. Analysis of scientific studies published on the function of char, its quantification, and its stability in soil. In An Assessment of the Benefits and Issues Associated with the Application of Biochar to Soil; Shackley, S., Sohi, S.P., Eds.; A Report to the Department for Environment, Food and Rural Affairs and the Department of Energy and Climate Change: London, UK, 2010; pp. 1–4.
[13]
Jeffery, S.; Verheijen, F.G.A.; van der Velde, M.; Bastos, A.C. A quantitative review of the effects of biochar application to soils on crop productivity using meta-analysis. Agric. Ecosyst. Environ. 2011, 144, 175–187, doi:10.1016/j.agee.2011.08.015.
[14]
Verheijen, F.G.A.; Jeffery, S.; Bastos, A.C.; van der Velde, M.; Diafas, I. Biochar Application to Soils—A Critical Scientific Review of Effects on Soil Properties, Processes and Functions; Office for the Official Publications of the European Communities: Luxembourg, 2009. EUR 24099 EN; p. 61.
[15]
Haefele, S.; Konboon, Y.; Wongboon, W.; Amarante, S.; Maarifat, A.; Pfeiffer, E.; Knoblauch, C. Effects and fate of biochar from rice residues in rice-based systems. Field Crops Res. 2011, 121, 430–441, doi:10.1016/j.fcr.2011.01.014.
[16]
Shackley, S.; Sohi, S.; Ibarrola, R.; Hammond, J.; Ma？ek, O.; Brownsort, P.; Haszeldine, S. Biochar as a Tool for Climate Change Mitigation and Soil Management. In Encyclopedia of Sustainability Science and Technology; Meyers, R., Ed.; Springer: New York, NY, USA, 2012; pp. 183–205.
[17]
Lehmann, J. Bio-energy in the black. Front. Ecol. Environ. 2007, 5, 381–387, doi:10.1890/1540-9295(2007)5[381:BITB]2.0.CO;2.
[18]
Glaser, B.; Lehmann, J.; Zech, W. Ameliorating physical and chemical properties of highly weathered soils in the tropics with charcoal—A review. Biol. Fertil. Soils 2002, 35, 219–230, doi:10.1007/s00374-002-0466-4.
[19]
Chan, K.Y.; Van Zwieten, L.; Meszaros, I.; Downie, A.; Joseph, S. Agronomic values of greenwaste biochar as a soil amendment. Aust. J. Soil Res. 2007, 45, 629–634, doi:10.1071/SR07109.
[20]
Saarnio, S.; Heimonen, K.; Kettunen, R. Biochar addition indirectly affects N2O emissions via soil moisture and plant N uptake. Soil Biol. Biochem. 2013, 58, 99–106, doi:10.1016/j.soilbio.2012.10.035.
[21]
Zavalloni, C.; Alberti, G.; Biasiol, S.; Vedove, G.D.; Fornasier, F.; Liu, J.; Peressotti, A. Microbial mineralization of biochar and wheat straw mixture in soil: A short-term study. Appl. Soil Ecol. 2011, 50, 45–51, doi:10.1016/j.apsoil.2011.07.012.
[22]
Case, S.J.; McNamara, N.P.; Reay, D.S.; Whitaker, J. The effect of biochar addition on N2O and CO2 emissions from a sandy loam soil—The role of soil aeration. Soil Biol. Biochem. 2012, 51, 125–134, doi:10.1016/j.soilbio.2012.03.017.
[23]
FAO. Food and Agriculture organization of the UN World soil resources online. Land and Water development division. WRB Map of World Soil Resources, 2002 updates. Available online: http://www.fao.org/ag/agl/agll/wrb/soilres.stm (accessed on 1 July 2010).
[24]
Bell, R.W.; Seng, V. Rainfed lowland rice-growing soils of Cambodia, Laos, and North-east. Thailand; ACIAR Proceedings No. 116e. In Water in Agriculture; Seng, V., Craswell, E., Fukai, S., Fisher, K., Eds.; Australian Centre for International Agricultural Research(ACIAR): Canberra, Australia, 2004; pp. 161–173.
[25]
Mulcahy, D.N.; Mulcahy, D.L.; Dietz, D. Biochar soil amendment increases tomato seedling resistance to drought in sandy soils. J. Arid Environ. 2013, 81, 222–225, doi:10.1016/j.jaridenv.2012.07.012.
[26]
Hilber, I.; Blum, F.; Leifeld, J.; Schmidt, H.P.; Bucheli, T. Quantitative Determination of PAHs in Biochar: A Prerequisite To Ensure its Quality and Safe Application. J. Agri. Food Chem. 2012, 60, 3042–3050.
[27]
Hale, S.; Lehmann, J.; Rutherford, D.; Zimmerman, A.; Bachmann, R.; Shitumbanuma, V.; O’Toole, A.; Sundqvist, K.; Arp, H.; Cornelissen, G. Quantifying the total and bioavailable polycyclic armoatic hydrocarbons and dioxins in biochar. Environ. Sci. Technol. 2012, 46, 2830–2838, doi:10.1021/es203984k.
[28]
Somtrakoon, K.; Chouychai, W. Phytotoxicity of single and combined polycyclic aromatic hydrocarbons toward economic crops. Russian J. Plant Physiol. 2013, 60, 139–148, doi:10.1134/S1021443712060155.
[29]
Biederman, L.A.; Harpole, W.S. Biochar and its effects on plant productivity and nutrient cycling: A meta-analysis. GCB Bioenergy, 2013, 5, pp. 202–214. Available online: http://onlinelibrary.wiley.com/doi/10.1111/gcbb.12037/full (accessed on 21 January 2013).
[30]
Food and Agriculture Organization of the UN Ecocrop data sheet—Brassica chinensis. Available online: http://ecocrop.fao.org/ecocrop/srv/en/dataSheet?id=547 (accessed on 27 September 2010).
[31]
Food and Agriculture Organization of the UN Ecocrop data sheet—Lactuca sativa. Available online: http://ecocrop.fao.org/ecocrop/srv/en/dataSheet?id=1313 (accessed on 27 September 2010).
[32]
Wunderground: Siem Reap Airport. Available online: http://www.wunderground.com/ (accessed on 4 July 2010).
