Effect of Carbonized Biomass Application on Carbon Accumulation and Soil Respiration.

Carbonized biomass is a carbon-rich solid product obtained by the pyrolysis of biomass. It could be used as a mechanism for long-term storage of C in soils. However, experimental results are variable. Objective of this study was carried out to evaluate the effect of carbonized biomass made from soybean residue on soil carbon and respiration during soybean cultivation. The carbonized biomass was made by field scale mobile pyrolyzer. Pyrolyzer was performed in a reactor operated at 400~500°C for 2 hours using soybean residue. A pot experiment with soybean in sandy loam soil was conducted for 133 days in a greenhouse, by a completely randomized design with three replications. The treatments consisted of four levels as the control without input and three levels of carbonized biomass inputs as 9.75 Mg ha^-1, C-1 ; 19.5 Mg ha^-1, C-2 ; 39 Mg ha^-1, C-3. It was appeared that soil respiration rate were 248.2 mg CO₂ m^-2 h^-1 for control, 334.4 mg CO₂ m^-2 h^-1 for C-1, 402.0 mg CO₂ m^-2 h^-1 for C-2 and 668.2 mg CO₂ m^-2 h^-1 for C-3 at the end of experiment. It was shown that the contents of soil carbon contents were 9.76 g kg^-1 for C-1, 13.43 g kg^-1 for C-2, 17.24 g kg^-1 for C-3 and 6.16 g kg^-1 for the control at the end of experiment. Accumulated soil carbon contents linearly significantly (P < 0.01) increased with increasing the carbonized biomass input. The slopes (0.282) of the regression equations suggest that soil carbon contents from the soil increases by 0.282 g kg^-1 more with every 1 Mg ha^-1 increase of carbonized biomass rate. Consequently the carbonized biomass for byproducts such as soybean residue could increase soil carbon. It might be considered that the experimental results will be applied to soil carbon sequestration for future study. More long-term studies are needed to prove how long does soil carbon stay in agricultural soils.