[Effect of modified ammonium bicarbonate on nitrification-denitrification process and NO and N2O emission]

Compared with ammonium bicarbonate(AB), the effect of modified ammonium bicarbonate (MAB) on nitrification and denitrification processes and NO and N2O emissions in a clay soil (C soil) and a loam soil (L soil) was studied in laboratory (25 degrees C and 50% WFPS). The inhibition effect of DCD from MAB on nitrification was relatively small in C soil, but considerably great in L soil. Compared with AB, MAB extended 7 days and 33 days for retaining NH4+. During 15 days, the NO emission from C soil and L soil respectively accounted for 0.60% and 1.06% of applied N under AB application (100 micrograms N.g-1), which were as 30 and 12 times as the N2O emission from corresponding soils. After applying MAB, the emission of NO from C soil and L soil decreased by 67% and 95%, and the emission of N2O decreased by 64% and 95%, respectively. After 39 days of aerobic incubation, then anaerobically flooded incubation with nitrate addition (200 micrograms KNO3-N.g-1) for 7 days, the total loss of denitrification in MAB in L soil was 50% less, and N2O emission was 113% more than in AB in same soil.