Three nitrogen chemical fertilizers were applied to soil - controlled-release urea (CU), a mixture of ammonium sulfate and urea with nitrification inhibitor (AM), and a mixture of ammonium sulfate and urea with no nitrification inhibitor (UA). N2O and NO fluxes from an Andosol soil in Japan were measured six times a day for three months with an automated flux monitoring system in lysimeters. The total amount of nitrogen applied was 20 g N m-2. The total N2O emissions from CU, AM and UA were 1.90, 12.7, and 16.4 mg N m-2, respectively. The total NO emissions from CU, AM and UA were 231, 152, and 238 mg N m-2, respectively. The total NO emission was 12-15 times higher than the total N2O emission. High peaks in N2O and NO emissions from UA occurred for one month after the basal fertilizer application. The N2O emissions from CU and AM during the peak period were 50% of those from UA, and the NO emissions were less than 50% of those from UA. After the peak period, the N2O and NO emissions from CU were the highest for two months. A negative correlation was found between the flux ratio of NO-N to N2O-N and the water-filled pore space. A diel pattern with increased N2O and NO fluxes during the day and with decreased fluxes during the night was observed.
