Table 1.
Physicochemical properties of the soil and biochar.
Fig 1.
The temporal change of a) soil temperature, gravimetric soil water content, and water filled pore space (WFPS), b) CO2 evolution from the soil with biochar and amendments.
c) Average soil CO2 emissions by different amendments. Four solid arrows show the urea and compost application events and two thick open arrows indicate the timing for biochar application. Error bars in c) represent the standard errors among the average data of the sampling dates.
Table 2.
Pearson correlation coefficients among CO2 emission rate, N2O emission rate, soil temperature, gravimetric water content, and hot water extractable C.
Fig 2.
Interactive effect between biochar and amendments on a) microbial activity and b) microbial biomass C in the soil.
Bars with different letters indicate significant differences in the average values of sampling dates among treatments at a 5% probably level.
Table 3.
Results of analysis of variance by date, biochar and amendments.
Table 4.
Seasonal change in the soil hot water extractable C (HWC) concentrations by biochar and amendments.
Comparison was made within the column by biochar and amendments within one date.
Fig 3.
Temporal change in total C contents influenced by biochar and amendments.
Bars with different letters indicate significant differences among treatments at a 5% probability level.
Fig 4.
The N2O emissions represented as a) the temporal changes from the soils with biochar and amendments and b) the average of the interactive effects between biochar and amendments.
Four solid arrows show the urea and compost application events and two thick open arrows indicate the timing for biochar application. Error bars in b) represent the standard errors among the average data of the sampling dates.
Fig 5.
Effects of biochar and amendments on the average amounts of NH4+ + NO3-.Bars with different letters indicate significant differences among treatments at a 5% probability level.
Fig 6.
Postulated N balance in the UREA soil with and without biochar addition.
Total amounts of urea N in the soil were assumed to be lost through N2O emission, NH3 volatilization and leaching and be remained in the soil as organic N and mineral N (NH4+ + NO3-). The amount of NH3 volatilization, plant biomass N and soil organic N were assumed to be the same between NO CHAR and CHAR treatments and not shown in the graph. Different letters beside the bars indicate significant differences between the NO CHAR and CHAR treatments at a 5% probability level.
Fig 7.
Effect of biochar and fertilization on soil water holding capacity (WHC).Bars with different letters indicate significant differences among treatments at a 5% probability level.