N2O and NO emissions from soils after the application of different chemical fertilizers

Abstract

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.