N2O and CO2 Emission from an Arable Soil Amended with Glucose and Alanine Addition

Laboratory incubation was conducted to investigate the effect of organic carbon species and nitrogen fertilizer type on the nitrous oxide (N₂O) and carbon dioxide (CO₂) at soil water content of 100%WHC. Dissolved nitrogen (NH₄ ⁺-N, NO₃ ^--N) and dissolved organic carbon (DOC) were also determined. The results showed the organic carbon species significantly affected the N transformation. For the ammonium fertilization (75 mg N kg^-1), maximal N₂O-N emission was found in the treatment with alanine addition (5.47 mg kg^-1), minimal emission in glucose addition (0.23 mg kg^-1), and medial emission in treatment with half alanine plus half glucose (1.87 mg kg^-1). The similar change trend of N₂O-N emission was also found in the equal rate of nitrate fertilization treatments. These results suggested amino acid-C had the higher bioavailability compared with the glucose. CO₂ emission was highest in the treatment with half alanine plus half glucose in both ammonium and nitrate fertilization. Minimal CO₂ emission was lowest in glucose addition treatment. Absence of NO₃ ^--N in all treatments after incubation indicated that denitrification was very strong in the experimental condition. Lowest DOC content was determined in the treatment with amino acid addition. N₂O emission was higher in nitrate fertilizer addition than in ammonium addition, and CO₂ emission was contrary.