Biochar addition to agricultural soils can improve soil fertility, with the added bonus of climate change mitigation through carbon sequestration. Conservation farming (CF) is precision farming, often combining minimum tillage, crop rotation and residue retention. In the present farmer-led field trials carried out in Zambia, the use of a low dosage biochar combined with CF minimum tillage was tested as a way to increase crop yields. Using CF minimum tillage allows the biochar to be applied to the area where most of the plant roots are present and mirrors the fertilizer application in CF practices. The CF practice used comprised manually hoe-dug planting 10-L sized basins, where 10%–12% of the land was tilled. Pilot trials were performed with maize cob biochar and wood biochar on five soils with variable physical/chemical characteristics. At a dosage as low as 4 tons/ha, both biochars had a strong positive effect on maize yields in the coarse white aeolian sand of Kaoma, West-Zambia, with yields of 444% ± 114% ( p = 0.06) and 352% ± 139% ( p = 0.1) of the fertilized reference plots for maize and wood biochar, respectively. Thus for sandy acidic soils, CF and biochar amendment can be a promising combination for increasing harvest yield. Moderate but non-significant effects on yields were observed for maize and wood biochar in a red sandy clay loam ultisol east of Lusaka, central Zambia (University of Zambia, UNZA, site) with growth of 142% ± 42% ( p > 0.2) and 131% ± 62% ( p > 0.2) of fertilized reference plots, respectively. For three other soils (acidic and neutral clay loams and silty clay with variable cation exchange capacity, CEC), no significant effects on maize yields were observed ( p > 0.2). In laboratory trials, 5% of the two biochars were added to the soil samples in order to study the effect of the biochar on physical and chemical soil characteristics. The large increase in crop yield in Kaoma soil was tentatively explained by a combination of an increased base saturation (from <50% to 60%–100%) and cation exchange capacity (CEC; from 2–3 to 5–9 cmol/kg) and increased plant-available water (from 17% to 21%) as well as water vapor uptake (70 mg/g on maize cob biochar at 50% relative humidity).
References
[1]
Lehmann, J. A handful of carbon. Nature 2007, 447, 143–144, doi:10.1038/447143a.
[2]
Beesley, L.; Moreno-Jimenez, E.; Gomez-Eyles, J.L.; Harris, E.; Robinson, B.; Sizmur, T. A review of biochar’s potential role in the remediation, revegetation and restoration of contaminated soils. Environ. Pollut. 2011, 159, 3269–3282, doi:10.1016/j.envpol.2011.07.023.
[3]
Woolf, D.; Amonette, J.E.; Street-Perrott, F.A.; Lehmann, J.; Joseph, S. Sustainable biochar to mitigate global climate change. Nat. Commun. 2010, 1, 1–9.
[4]
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.
[5]
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.
[6]
Lehmann, J.; da Silva, J.P.; Steiner, C.; Nehls, T.; Zech, W.; Glaser, B. Nutrient availability and leaching in an archaeological anthrosol and a ferralsol of the central amazon basin: Fertilizer, manure and charcoal amendments. Plant Soil 2003, 249, 343–357, doi:10.1023/A:1022833116184.
[7]
Asai, H.; Samson, B.K.; Stephan, H.M.; Songyikhangsuthor, 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 Crop. Res. 2009, 111, 81–84, doi:10.1016/j.fcr.2008.10.008.
[8]
Hossain, M.K.; Strezov, V.; Yin Chan, K.; Nelson, P.F. Agronomic properties of wastewater sludge biochar and bioavailability of metals in production of cherry tomato (Lycopersicon esculentum). Chemosphere 2010, 78, 1167–1171, doi:10.1016/j.chemosphere.2010.01.009.
[9]
Major, J.; Rondon, M.; Molina, D.; Riha, S.; Lehmann, J. Maize yield and nutrition during 4 years after biochar application to a colombian savanna oxisol. Plant Soil 2010, 333, 117–128, doi:10.1007/s11104-010-0327-0.
[10]
Steiner, C.; Glaser, B.; Teixeira, W.G.; Lehmann, J.; Blum, W.E.H.; Zech, W. Nitrogen retention and plant uptake on a highly weathered central amazonian ferralsol amended with compost and charcoal. J. Plant Nutr. Soil Sci. 2008, 171, 893–899, doi:10.1002/jpln.200625199.
[11]
Yamato, M.; Okimori, Y.; Wibowo, I.F.; Anshori, S.; Ogawa, M. Effects of the application of charred bark of acacia mangium on the yield of maize, cowpea and peanut, and soil chemical properties in south sumatra, indonesia. Soil Sci. Plant Nutr. 2006, 52, 489–495, doi:10.1111/j.1747-0765.2006.00065.x.
[12]
Chidumayo, E.N. Effects of wood carbonization on soil and initial development of seedlings in miombo woodland, zambia. Forest Ecol. Manag. 1994, 70, 353–357, doi:10.1016/0378-1127(94)90101-5.
[13]
Novak, J.M.; Busscher, W.J.; Watts, D.W.; Amonette, J.E.; Ippolito, J.A.; Lima, I.M.; Gaskin, J.; Das, K.C.; Steiner, C.; Ahmedna, M.; Rehrah, D.; Schomberg, H. Biochars impact on soil-moisture storage in an ultisol and two aridisols. Soil Sci. 2012, 177, 310–320.
[14]
Kimetu, J.; Lehmann, J.; Ngoze, S.; Mugendi, D.; Kinyangi, J.; Riha, S.; Verchot, L.; Recha, J.; Pell, A. Reversibility of soil productivity decline with organic matter of differing quality along a degradation gradient. Ecosystems 2008, 11, 726–739, doi:10.1007/s10021-008-9154-z.
Warnock, D.; Lehmann, J.; Kuyper, T.; Rillig, M. Mycorrhizal responses to biochar in soil—Concepts and mechanisms. Plant and Soil 2007, 300, 9–20, doi:10.1007/s11104-007-9391-5.
[17]
Haefele, S.M.; Konboon, Y.; Wongboon, W.; Amarante, S.; Maarifat, A.A.; Pfeiffer, E.M.; Knoblauch, C. Effects and fate of biochar from rice residues in rice-based systems. Field Crop. Res. 2011, 121, 430–440, doi:10.1016/j.fcr.2011.01.014.
[18]
Steiner, C.; Teixeira, W.G.; Lehmann, J.; Nehls, T.; de Macedo, J.L.V.; Blum, W.E.H.; Zech, W. Long term effects of manure, charcoal and mineral fertilization on crop production and fertility on a highly weathered central amazonian upland soil. Plant Soil 2007, 291, 275–290, doi:10.1007/s11104-007-9193-9.
[19]
Chan, K.Y.; Xu, Z. Biochar: Nutrient properties and their enhancemen. In Biochar for Environmental Management: Scienceand Technology; Joseph, S., Lehmann, J., Eds.; Earthscan: London, UK, 2009.
[20]
Wisnubroto, E.I.; Hedley, M.; Hina, K.; Camps-Arbestain, M. The Use of Biochar from Biosolids on Waitarere Sandy Soils: Effect on the Growth of Rye Grass. the New Zealand Biochar Research Centre Workshop Massey University, Palmerton North, New Zealand, 10–11 February 2011.
[21]
Bridle, T.R.; Pritchard, D. Energy and nutrient recovery from sewage sludge via pyrolysis. Water Sci. Technol. 2004, 50, 169–175.
[22]
Hale, S.E.; Lehmann, J.; Rutherford, D.; Zimmerman, A.R.; Bachmann, R.T.; Shitumbanuma, V.; O’Toole, A.; Sundqvist, K.L.; Arp, H.P.H.; Cornelissen, G. Quantifying the total and bioavailable polycyclic aromatic hydrocarbons and dioxins in biochars. Environ. Sci. Technol. 2012, 46, 2830–2838, doi:10.1021/es203984k.
[23]
Hobbs, P.R.; Sayre, K.; Gupta, R. The role of conservation agriculture in sustainable agriculture. Phil. Trans. R. Soc. B 2008, 363, 543–555, doi:10.1098/rstb.2007.2169.
[24]
Giller, K.E.; Witter, E.; Corbeels, M.; Tittonell, P. Conservation agriculture and smallholder farming in africa: The heretics view. Field Crop. Res. 2009, 114, 23–34, doi:10.1016/j.fcr.2009.06.017.
[25]
Aagaard, P.J. The practice of conventional and conservation agriculture in east and southern Africa. Conserv. Farm. Unit Zambia June 2011, 1, 35–39.
[26]
Haggblade, S.; Tembo, G. Conservation Farming in Zambia; EPTD Discussion Paper 108; International Food Policy Research Institute (IFPRI): Washington, DC, USA, 2003.
[27]
Umar, B. Options for improving smallholder conservation agriculture in zambia. J. Agric. Sci. 2011, 3, 50–62.
[28]
Hill, R.L.; Horton, R.; Cruse, R.M. Tillage effects on soil water retention and pore size distribution of two mollisols. Soil Sci. Soc. Am. J. 2004, 49, 1264–1270, doi:10.2136/sssaj1985.03615995004900050039x.
[29]
Rutherford, D.W.; Wershaw, R.L.; Reeves, J.B., III. Development of Acid Functional Groups and Lactones during the Thermal Degradation of Wood and Wood Components; Paper for U.S. Geological Survey Scientific Investigations: Denver, CO, USA, 2008.
[30]
Chivenge, P.; Vanlauwe, B.; Six, J. Does the combined application of organic and mineral nutrient sources influence maize productivity? A meta-analysis. Plant Soil 2010, 342, 1–30, doi:10.1007/s11104-010-0626-5.
[31]
Mulder, J.; van Breemen, N.; Eijck, H.C. Depletion of soil aluminium by acid deposition and implications for acid neutralization. Nature 1989, 337, 247–249, doi:10.1038/337247a0.
[32]
Hale, S.E.; Alling, V.; Martinsen, V.; Mulder, J.; Cornelissen, G. The adsorption and desorption of phosphate-P, ammonium-N and nitrate-N infrom unwashed and washed biochars. Chemosphere 2013. in press.
