Effects of biochar application on biological characteristics and respiration rate of Cd contaminated soil

【Objectives】This paper aimed to study effects of biochar on soil biological characteristics and soil respiration rate of Cd contaminated soil.【Methods】Experiment was carried out in 2016 by means of pot plants (25kg soil per pot). The added exogenous Cd concentrations were 0mg/kg (G0), 30mg/kg (G1), 60 mg/kg (G2) and the biochar concentrations were 0g/kg (T0), 10g/kg (T1), 20g/kg (T2) respectively. A total of nine treatments were used for the two-factor test, which were G0T0, G0T1, G0T2, G1T0, G1T1, G1T2, G2T0, G2T1, G2T2. Soil microorganisms and soil microbial biomass (carbon, nitrogen), soil enzyme activity and soil respiration rate were measured in different periods. Results showed that soil urease activity, number of soil bacteria and actinomycetes and soil microbial biomass carbon and microbial biomass nitrogen and soil respiration rate increased significantly along with the application of biochar, and all reached higher level 55d after transplanting. Soil respiration rate increased with growth period, and soil respiration rate increased significantly with the increase of biochar application in heavily Cd contaminated soil. 【Conclusions】Application of biochar can significantly improve biological characteristics of Cd contaminated soil and improve soil respiration rate, so as to improve quality of Cd contaminated soil.