SOIL RESPIRATION ON TWO METHODS OF BIOCHAR APPLICATIONS AND ITS RELATED EFFECT ON SOIL NUTRIENT
Oraegbunam C. J. 1* and Uchida Y2
1Graduate School of Agriculture, Hokkaido University Japan
2Research Faculty of Agriculture, Hokkaido University Japan
*Corresponding author: johnsondozie@gmail.com

Soil quality is measured by its ability to support plant and microbial growth and to retain nutrients without loss. Organic materials added to the soil in a pyrolyzed form (charcoal or called "biochar") are known to have a potential to improve soil quality but its efficacy may depend on the method of application (incorporated or surface applied).
Chicken manure (CM), rice husk (RH) and rice straw (ST) were charred to produce biochar under 350°C, applied to the soil grown with dent corn using two method (mixed or surface-applied). Soil respiration R_S was measured. The soils were leached, the leachate was sampled for soluble organic carbon (TOC) and nitrate analysis. Plant biomass and microbial biomass carbon (MBC) was also determined.
There was no clear difference in R_S between the application methods. Mixed was higher in plant biomass (0.025 kg kg^-1 of soil) and TOC (4.17 mg C L^-1) but lower in MBC (76.05 mg kg^-1) than surface. Soils with biochar showed lower nitrate (3.24 NO3^--N mg L^-1) leached than control (5.98 NO3^--N mg L^-1) without biochar. CM released more C (6.34 mg C L^-1) than other materials. Thus, we concluded that the method should be determined based on organic matter type.