Fast pyrolysis biochar from sawdust improves the quality of desert soils and enhances plant growth

BACKGROUND: Biochar has been mostly used in conventional arable soils for improving soil fertility. This study investigated the effect of biochars of different temperatures on plant growth and desert soil properties. Biochars of different temperatures (i.e. 400, 500, 600, 700, and 800 degrees C) were mixed in the soil with 5% by mass, and the treatments were designated as T-400, T-500, T-600, T-700 and T-800, respectively. Sorghum was used as a test crop, and the effect of biochar on plant height, yield and soil properties was evaluated. RESULTS: Sorghum yield increased by 19% and 32% under T-400 and T-700, respectively, above the control. Biochar reduced depth-wise moisture depletion in soil columns and hence improved soil water-holding capacity by 14% and 57% under T-400 and T-700, respectively. Soil hydraulic conductivity was reduced by 15% and 42%, and moisture-retention capacity was improved by 16% and 59%. Hence, sorghum net water-use efficiency increased by 52% and 74% in T-400 and T-700, respectively. Biochar also improved soil total carbon, cation exchange capacity and plant nutrient content. CONCLUSION: The addition of fast pyrolysis biochar made from pine sawdust improved the quality of Kubuqi Desert soil and enhanced plant growth. Hence, it can be used for desert modification. (C) 2015 Society of Chemical Industry