Characterization and Effect of Biochar on Nitrogen and Carbon Dynamics in Soil

In the current study the biochar material was produced by the indigenous pyrolysis of prosopis wood material under high temperature and characterized. The impact of biochar on carbon and nutrient dynamics in soil was examined by conducting a laboratory closed incubation experiment. The biochar produced from prosopis was neutral in pH with an exchangeable acidity of 49 mmol kg. The cation exchange capacity was 16 cmol kg. It had relatively higher potassium (K) content than nitrogen (N) and phosphorus (P). The carbon content was very high (940 g kg). One of the major characteristics of biochar that makes it attractive as a soil amendment is its high porous structure, potentially responsible for improved water retention and increased soil surface area. Upon incorporation of different rates of biochar in a soil (pH 8.42) the pH decreased up to 7.92 during incubation; whereas, the cation exchange capacity (CEC) of soil was found significantly increased due to biochar addition. The soil organic carbon (SOC) markedly increased with an increase in rate of application of biochar, which was further increased during the 90 days of incubation. This suggests that the biochar has great potential for carbon sequestration in soil. While marked increase in soil microbial biomass carbon and humic & fulvic acid fraction of SOC was evident during incubation, there was not much change in water soluble organic carbon due to biochar incorporation. The mineral – N, comprising of ammoniacal nitrogen (NH4-N) and nitrate nitrogen (NO3-N), concentration has shown significant reduction when different rates of biochar were added to soil. Increase in the rate of application markedly reduced the concentration of both NH4-N and NO3-N. During incubation further decrease in the concentration was observed. The results suggest that the carbon and nutrient dynamics in soil affected due to biochar incorporation may have a significant role in the reduction of GHGs (particularly CO2 and N2O) emission from soil. Further research on the effect of biochar on GHG emission is in progress.