NITROUS OXIDE AND CARBON DIOXIDE EMISSIONS FROM AGRICULTURAL SOIL AMENDED WITH DIFFERENT TYPES OF BIOCHAR AT THREE TEMPERATURES

抄録

   A laboratory experimental study was conducted to investigate the effects of different coffee waste biochar materials at three temperatures on nitrous oxide (N₂O) and carbon dioxide (CO₂) emissions from agricultural soil in Central Vietnam. Soil amended with 2% normal biochar, 2% functional biochar (with a high NO₃-N adsorption capacity of 20 g N kg^-1) or no addition was adjusted at 60% water holding capacity, conditioned with 100 mg N-NO₃ kg^-1 dried-soil and aerobically incubated at 25℃, 30℃ or 35℃ for 21 days. N₂O and CO₂ emissions were measured on days 1, 3, 5, 7, 14 and 21. Results showed that the addition of normal biochar caused more CO₂ emission but less N₂O emission compared to the functional biochar application. At 25℃, biochar amendment had a neutral or positive effect on N₂O and CO₂ emissions. At 35℃, biochar amendment reduced N₂O and CO₂ emissions compared to the control. However, there was little difference in N₂O and CO₂ emissions among biochar treatments. In addition, with increasing temperature, a positive correlation between temperature and N₂O and CO₂ emissions with the non-biochar amendment and a negative correlation between temperature and N₂O with the biochar treatments were observed. This is because temperature probably affects the rate of microbial processes mediating respiration and denitrification and the soil-biochar mixture's mobilization of N availability.