| Summary: | A field study involving wheat production was extended in order to study the effects of biochar (BC) amendment in paddy soil that had long-term contamination of Cd. The BC was used as an amendment in Cd-contaminated soil for its special property. BC was amended at rates of 10 to 40 t ha-1 during the rice season before rice transplantation in 2009. BC amendments increased soil pH by 0.11 to 0.24 and by 0.09 to 0.24 units, respectively, while the soil CaCl2-extracted Cd was reduced by 10.1% to 40.2% and by 10.0% to 57.0% in 2010 and 2011, respectively. Consequently, the total wheat Cd uptake was decreased by 16.8% to 37.3% and by 6.5% to 28.3%. Wheat grain Cd concentration was reduced by 24.8% to 44.2% and by 14.0% to 39.2% in 2010 and 2011, respectively. The BC application in soil reduced Cd phyto-availability in two wheat seasons possibly by raising soil pH and soil organic carbon (SOC). Therefore, BC may be used for soil remediation, but not to reduce Cd uptake to an adequate level for food production on Cd contaminated soils.
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